Identifying players you can “buy low” on in fantasy baseball season is always a fun but stressful experience. What does “Buy Low” mean? What if the player just isn’t any good? What if the advanced metrics will always paint a rosier picture than the actual results? There are so many questions that we need to contend with. In this article, I’ll go over one of the ways I like to identify pitchers who might be due for a positive swing in results: SIERA leaderboards.
SIERA is one of my favorite in-season and pre-season stats to look at when I’m not obsessing over pitch mixes. It stands for Skill-Interactive Earned Run Average and, according to its definition, it “quantifies a pitcher’s performance by trying to eliminate factors the pitcher can’t control by himself.” That means, unlike stats like xFIP or ERA, SIERA considers balls in play and adjusts for the type of ball in play to determine what a pitcher’s results “should have been” based on probability. In that respect, SIERA has been tested as the most predictive of all ERA estimators, meaning a pitcher’s SIERA from a previous season is more likely to indicate their future ERA than xFIP or past ERA, etc.
So let’s put that to the test.
Identifying Potential Breakout Starting Pitcher
One of my favorite exercises at the start of every season is to create a leaderboard of starting pitchers who most underperformed their SIERA in the previous season. That gives me a baseline of pitchers who may have “deserved” better results. This year, I took that a step further and also removed all pitchers who had below-league-average swinging strike rates (SwStr%), Stuff+ numbers, and K-BB%. In my mind, this tells me not just which pitchers should have positive regression based on their SIERA but also highlights which pitchers among that group have the best raw stuff and strikeout upside. I understand that’s double counting to a certain extent, but I am a believer in following “Stuff” and strikeouts when trying to find pitchers who can provide me with value at cost, so I wanted to test that here.
The league average for those metrics I mentioned above was a 10.7% SwStr%, 14.4% K-BB%, and 98 Stuff+ grade. Using those as a cutoff cost us pitchers like Kenta Maeda, Taijuan Walker, and Kyle Hendricks, who all had far worse ERAs than their SIERA but also had far worse swinging strike rates and Stuff+ metrics than the league average. We lost Jordan Montgomery because his Stuff+ grade last year was subpar, and we also lost Bobby Miller, who only had a 9.9% SwStr%; however, I made the case for Miller as a late-round dart throw in my article on late-round starting pitcher targets. We also had to get rid of Walker Buehler, who missed the cut in both K-BB% and SwStr%, but I like him at cost right now because I think we’re going to see a much healthier season out of him and Boston should tweak his pitch mix a bit to limit his reliance on a declining four-seam fastball.
So who did that leave?
There are plenty of interesting names on there, but I’m not going to cover all of them. Some of them are mentioned in other articles I’ve written, so I’ll link to those below, but let’s try and hit some of the highlights.
First of all, I’m not sure anybody needs to be convinced that Garrett Crochet, Tyler Glasnow, and Joe Ryan are really good pitchers. I have them all inside my top 20 in my Top 150 Starting Pitchers article, and I’d be happy to draft any of them (provided Glasnow is healthy). I do think this is YET ANOTHER great signal for anybody who is worried about Crochet’s second half last year that it was purely a result of the White Sox messing around with his innings. The guy is a bonafide stud.
I also think most people believe that Spencer Arrighetti‘s ERA is a bit misleading because we know that it’s influenced by the struggles in his first few starts. His first 80 innings featured a 12% walk rate and a 1.60 WHIP compared to the 7.9% walk rate and 1.17 WHIP in his final 65 innings where he also posted a 3.18 ERA and 29.3% strikeout rate. Since it’s just a 65-inning sample, we can’t say that new level is definitely who Arrighetti is, but we love how he adjusted to MLB hitters and that he has a deep arsenal to create varied attack plans, which means I think it’s safe to say he’s closer to the second-half guy than the first-half guy.
I know we often make the case for Nick Pivetta, and he’s certainly pitching in the best home stadium he’s ever pitched in, but Pivetta has also had a lower SIERA than ERA in every single one of his MLB seasons. In fact, as Nick Pollack pointed out on Twitter, it’s wild to know that Pivetta has been an MLB starter for seven full MLB seasons and HAS NEVER pitched to an ERA under 4.00. The lowest ERA of his career was a 4.04 mark with Boston in 2023. That came with a 3.36 SIERA, but he still posted a 4.14 ERA last season. I’m not sure why that would change now.
Jesus Luzardo is on here, but I don’t want to go into too much detail on him because we know he was pitching through multiple injuries last year. Luzardo is a solid starter who is now in a much better team situation in Philadelphia. He’s never been a good bet for health, so you have to factor that into your innings calculus, but he’s always going to be pretty good when he’s on the mound.
We also don’t need to spend too much time on veterans like Eduardo Rodriguez and Andrew Heaney because we know who they are at this point. Rodriguez was hurt last year and only threw 50 innings, but he didn’t look like that much of a different pitcher in his innings. His velocity was down but not by much, and his command was not as sharp after the layoff, which is to be expected. I think he’ll likely settle in with an ERA around 4.00 and a 22% strikeout rate and be fine in Arizona. I also think Heaney has always been a pitcher you enjoy having on your roster for stretches and then somebody you don’t want to play against elite offenses. I don’t think that changes much in Pittsburgh; although, I’m a little worried about his dip in velocity. His team context is worse, but he’s going to get the ball every fifth day when he’s healthy and pitch to an ERA in the low 4.00s with about a 23.5% strikeout rate on a team that won’t win tons of games.
Reid Detmers – Los Angeles Angels
This is now the third article where Reid Detmers has popped up in my offseason research, and I promise I’m not intending to be the “Reid Detmers Guy.” As I mentioned in one of my previous articles, Nick Pollack and I recorded an episode of “On the Corner” where we made a leaderboard of three stats we look at regularly with starting pitchers. We included swinging strike rate, PLV, which is the Pitcher List pitch grading metric that factors in command, and Str-ICR, which is a Pitcher List stat that measures how many strikes a pitcher throws and subtracts Ideal Contact Rate (ICR) allowed, meaning that it shows what pitchers throw a lot of strikes and don’t get hit hard. We then looked at the starting pitchers who finished in the top 20% in all categories, the top 25% in all categories, and the top 33% in all categories. Even in a down year in 2024, Detmers’ swinging strike rate was 85th percentile in baseball among starters, his Str-ICR was 74th percentile, and his PLV was 67th percentile. The raw ability is most certainly still there.
One thing I was particularly interested in last year was the change Detmers made to his fastball. In addition to adding extension on the pitch, Detmers added significant iVB, up to 17.1 inches, which is well above average. Considering Detmers likes to throw that fastball up in the zone, the added iVB is nice to see. It might also be part of the reason why the Ideal Contact Rate (ICR) on the pitch dropped from over 47% down to 40%, and the swinging strike rate went up to an 82nd-percentile mark. It had a slightly below-average zone rate and a league-average strike rate, but he’s clearly working to improve it. His slider also had a huge leap in PLV grade in part by reducing the velocity by almost three mph and adding more horizontal break, which led to an 18.2% SwStr% to lefties.
Detmers’ biggest issue is command. His slider gets hit hard because he can throw it over the plate consistently, but he doesn’t always bury it at the bottom of the strike zone. Detmers also has the same issue with his curveball. If he can command his secondaries better then we could see a real breakout, which is why SIERA is telling us that there is some actual upside here.
David Festa – Minnesota Twins
I like David Festa. He has struggled a little bit with walks and home runs in the upper levels of the minors, which has kept his ratios from being elite, but he has consistently missed bats with a 35% strikeout rate in Triple-A last year. His first two big league starts didn’t go well last season, but he posted a 3.81 ERA, 1.25 WHIP, and 30% strikeout rate in his next 12 appearances, which shows a great ability to adjust to big league hitters.
One of the ways he adjusted was to lean into his slider more, throwing it about 24% of the time in his first few appearances and up around 33% of the time in his final five appearances. That’s good because the slider has the potential to be a nice pitch for him. It grades out well in PLV because Festa has good control of it with strong zone rates and strike rates. It doesn’t miss as many bats as we’d like, but I think a lot of that has to do with locations. Festa needs to get better at burying the slider down in the zone. I also think the slider could be improved by the new sinker Festa has added. If he can get the sinker in on the hands of righties then that should open up the outside part of the plate for the slider to be more effective. The sinker would also help because Festa’s four-seamer had a 6th-percentile ICR to right-handed hitters and gave up a 36.4% HR/FB rate. If Festa can use the sinker early in the counts to righties to prevent hard contact then he can also use the four-seamer up in the zone for swings and misses but rely on it less overall.
The biggest issue for Festa is that he may not start the year in the rotation if the Twins are committed to keeping Chris Paddack there. That could mean Festa goes to Triple-A for the first few weeks of the season until a spot opens up, but that’s the only thing keeping him from being a real target for me in drafts.
Brandon Pfaadt – Arizona Diamondbacks
This is not going to be a ringing endorsement because I’m not that interested in Brandon Pfaadt. I’ve never been a huge fan, in terms of the belief that he can be an ace. He gives up a lot of hard contact with a 40.2% ICR last season which was worse than the 38.6% MLB average for starting pitchers. His 19% balls-in-play rate is also worse than the league average and is another indicator that he’s not fooling hitters, and they’re able to make plenty of contact.
Much of that is because he’s essentially just a four-seam/sweeper pitcher with a sinker that he mixes in to righties. I guess he does throw the sinker 14% of the time to lefties, but it performs poorly against them, so the only effective pitch he has to lefties is his changeup, which took a step forward in 2024. Pfaadt’s sweeper has a better-than-league-average swinging strike rate to lefties but a gross 50% ICR and 33.3% HR/FB ratio, so it’s not a pitch he should throw to them often. On top of that, the four-seamer also gets hit often and hard by lefties, so he doesn’t really have a pitch to lefties he can just throw to get ahead in the count or get weak contact. We’ve also been saying this for two years now and that hasn’t changed.
In fact, Pfaadt’s splits got WORSE in 2024. He allowed a .294/.339/.472 slash line to lefties last year with just a 19% strikeout rate. I know SIERA is interested in him as a “buy-low” type of pitcher, but until I see that he can get lefties out, I can’t believe in him.
Nick Lodolo – Cincinnati Reds
The issue for Nick Lodolo is pretty much always health. In his first 11 starts of 2024, Lodolo posted a 2.76 ERA and 1.01 WHIP, with a 26% strikeout rate. We forgot that because he dealt with injuries AGAIN and was ineffective for the remainder of the season, but the talent is still in there. He has two fastballs he can use against righties and lefties, and both a curve and change which means he can attack hitters of each handedness with a secondary as well. Those are all things we love from any starting pitcher.
However, his arm angle is a bit of a gift and a curse. His low release point causes him to almost “sling” the ball to the plate, which is why he gets greater horizontal movement on many of his pitches, but it also causes his command to go in and out. His career zone rate of 45.3% is below league average, as is his career 63.5% strike rate. That puts an awfully lot of pressure on him to get swings and misses out of the zone, which he has been able to do during his career, but makes him inconsistent. When you add his many health red flags and his bad home ballpark, it’s hard to know exactly what you’ll get from him. However, given how late he’s going and how productive he’s been when healthy, I’m happy to gamble here.
Edward Cabrera – Miami Marlins
Ah, yes, here we are again with Edward Cabrera. What SIERA loves is his 99 Stuff+ grade and his 11.9% SwStr%, both of which are better than the league average. However, what it probably hates is his 1.37 WHIP and 42% zone rate. Yet, that’s why the SIERA was 4.22 and not something ace level.
Cabrera has a 96.3 mph four-seamer with above-average extension that should miss more bats than it does, but his locations on the pitch are terrible. A lot of that has to do with poor command which causes Cabrera to try and just throw the four-seamer for strikes, but it was located in the middle of the zone about 40% of the time last year. That’s not going to fly and is a big reason why it had a nearly 50% ICR and below-average swinging strike rates.
His changeup is his best pitch, and it absolutely ate up righties last year with a 24% swinging strike rate (SwStr%) and a 21.4% ICR. It had previously performed as well against lefties, but his command of the pitch suffered last year. In 2023 he threw it low in the zone 72% of the time, but that fell to 64% in 2024 because he was leaving the changeups over the middle of the plate too often to lefties. That led to a big decrease in SwStr% and a huge increase in ICR.
He also has both a curve and a slider that could be intriguing. The curve is a pitch he commands well and gets a decent amount of swinging strikes with, but it also gets hit relatively hard, so it’s not something we want him relying on too much. The primary concern is, stop me if you’ve heard this before, he throws the pitch for strikes a decent amount but doesn’t really bury it low in the zone, so it can catch too much of the middle of the plate and get hammered. Last season, he turned his slider into a bit more of a cutter at 90 mph and was able to locate it in the zone better. It doesn’t miss a ton of bats but also doesn’t allow a lot of contact, so if that is a cutter then maybe it can help his changeup play up to lefties and take pressure off of his four-seamer to righties.
At the end of the day, I share SIERA’s optimism about Cabrera’s raw stuff, but I need to see more precise command before I buy in. Still, that means I love taking late fliers in drafts and then seeing how his command looks this spring.
Gavin Williams – Cleveland Guardians
I think I’ve also written about Gavin Williams three times this off-season, so I’d encourage you to read my Post-Hype Starting Pitcher article, where I dive into Williams in detail. Needless to say, I’m expecting a big year.
Hayden Birdsong and Kyle Harrison – San Francisco Giants
The two teammates both appeared on this list, and I know they’re two young pitchers who have their fans in the fantasy baseball community. We should start by saying that it seems unlikely Birdsong makes the rotation out of spring training, so he’s likely to start the year in Triple-A.
That being said, there are some intriguing aspects to Birdsong’s pitch mix. For starters, the slider is a good pitch and a potential neutralizer for righties. It posted a 24% swinging strike rate and 44.4% CSW against them in 2024, and he’s able to throw the pitch in the zone a decent amount. His curveball also grades out well in terms of pure stuff, but he struggles to command it in the zone against both righties and lefties. Considering his four-seam fastball doesn’t miss bats at all, Birdsong needs the slider and curve to be consistently successful if he’s going to be a good MLB pitcher. They can be from a shape/movement standpoint, but until his command of those offerings improves, which can often be hard to do, it’s hard to get overly excited about Birdsong having some kind of breakout.
Coming into this season, I was higher on Birdsong than I was on Kyle Harrison. I just honestly don’t quite see it with Harrison. He throws his fastball essentially 60% of the time to both righties and lefties, and it grades out as a slightly above-average pitch. He doesn’t get great velocity on it, but it has plenty of horizontal movement (or run), which is why he lives with it up and away to righties and up and in to lefties. The pitch has produced slightly above-average swinging strike rates to both, but righties hit it a little better, which makes sense since he keeps it out and over the plate.
Apart from that, he has a curveball that misses bats to lefties and is in the zone often but gets clobbered by righties and a changeup that he has only average command of but doesn’t miss bats to righties and gets hit hard by lefties. There’s not a lot there that adds up to being a useful fantasy starter.
However, we also have the news that Harrison is adding a cutter this off-season. Now, this is the second straight off-season we’ve gotten that rumor, so we need to take it with a grain of salt, but this time Harrison himself is talking about the cutter (and his refined mechanics). We know that Harrison threw a harder gyro-type slider in the minors, so that’s likely the pitch he’s referring to, and I love that addition for him. Let’s talk about why.
When he faces righties he basically only has the fastball, which he keeps middle or away 81% of the time, and the changeup, which he throws middle or away 84% of the time. He doesn’t even like throwing the curve inside to righties because they clobber it, so he essentially has no pitch that he can attack righties with inside. The cutter or gyro slider would be that. Depending on its movement profile, he could jam hitters up and in with it, which might reduce its swing-and-miss upside but would keep righties from leaning out over the plate which would make the low-and-away changeup more effective and also further increase the swings and misses on the fastball that runs away from righties. If the shape/movement of the gyro slider/cutter is something he can get swings and misses with down and in then he’d still be attacking righties inside but would have them looking down and in which would allow the up-and-away fastball to play up more and could even make the loopier slurve type curveball he has more effective since they’d attack the same zone but at vastly different speeds and with different sharpness of breaks.
When he’s facing lefties he can then jam them inside with the running four-seam fastball and then use the combination of the slurve and gyro slider/cutter to attack lefties away with various speeds and movement profiles that could tunnel well with one another. Considering Harrison has toyed with this pitch before and not actually implemented it, I don’t want to get too excited, but I’d love this if it came to fruition.
Jared Jones – Pittsburgh Pirates
I had been higher on Jones, but Nick Pollack talked me down a bit as we went through our off-season “On the Corner” podcast episodes. The long and short of it is that Jones has an elite four-seam and slider combo that worked well for Spencer Strider and can certainly work well for Jones. However, Jones seemed unable to maintain fastball velocity as his starts went on, and so the pitch got hit harder deeper into games. We also saw his iVB fall as the season went on; of course, he was also coming back from a lat injury, so maybe that had more to do with the diminished effectiveness of the fastball, but we can’t be entirely sure until we see him on the mound in real games again.
Yet, Jones could be adding a new wrinkle this off-season because he has hinted at adding a sinker to his pitch mix. That would put even less pressure on his four-seamer to hit those early season highs. Even though Jones’ four-seamer was good against righties in 2024, he had a lower swinging strike rate than against lefties and didn’t seem to like to come inside to righties, with just a 21% inside rate versus a 30% inside rate when he used the four-seamer against lefties. Jones could use this new sinker in on the hands of righties and get strikes and weak contact early in the count, which would allow his four-seamer and slider to play up even more for strikeouts. We love that.
Jones throws a consistent amount of strikes, and the addition of the sinker should allow the rest of the arsenal to play up. That’s to say nothing of his reported off-season work on refining his curveball and changeup. If Jones can find that consistent third strike and keep righties off his four-seamer, we could be looking at a top-25 starter in fantasy, so I trust SIERA here.
Taj Bradley – Tampa Bay Rays
We still dream about what could be with Taj Bradley, and his presence on this leaderboard is certainly going to continue to have us doing that. Everybody is going to remember that nine-start stretch over June/July where he posted a 0.82 ERA, 0.89 WHIP, and 31% strikeout rate over 55 innings, and it’s hard to blame you. He had his four-seam fastball working up in the zone and his new splitter dropping under the strike zone, and he was carving hitters up, but the issue for Bradley is always consistent command. He was unable to keep command of his fastball consistently up in the zone, and so the two-pitch approach became less efficient. From July 31st on, he posted a 6.51 ERA, 1.54 WHIP, and 22.4% strikeout rate in 56.2 innings. That’s pretty gross.
Much like with Brandon Pfaadt, Bradley has issues against lefties. They’re not as bad as Pfaadt’s, but Bradley’s four-seam gets hit hard by lefties with a 52% ICR, 93.3 mph average exit velocity allowed, and 14.6% barrel rate. He does have a cutter that performs better, but he only throws it 18% of the time to lefties and has mediocre command of it. He also uses it low in the zone a lot, so increasing its usage would still mean he doesn’t attack up in the zone to lefties with anything other than his four-seamer. His splitter also misses a good deal of bats against lefties but allows a lot of hard contact when it’s hit and a 23.1% HR/FB to lefties, which is less than ideal.
I want to believe in Bradley, and I believe in him more than Pfaadt, but I think he will always have some inconsistencies due to his overall lack of command. If he uses that cutter up and inside more to lefties then I think he can take another step forward, but I don’t see a major breakout here, and I’m not sure we’ll ever see the 3.69 ERA that SIERA hints at.
DJ Herz – Washington Nationals
Is DJ Herz in the Nationals’ rotation? I mean, it seems like he should be after he flashed good upside last year, but the Nationals signed Michael Soroka this off-season and said he was a starter and then also have McKenzie Gore, Jake Irvin, MitchellParker, and Trevor Williams. Herz has more upside than almost all of those guys, but the Nationals seem like a team that wants those veterans to start the year in the rotation so they can trade them if they succeed or try and make a surprise push for the postseason.
If Herz does make the rotation, the biggest issue for him will be command. Having a nearly 10% walk rate is not going to cut it, and those command concerns were a huge part of his prospect profile. Herz also had some potentially flukey success in 2024. His four-seam fastball had a nearly 16% swinging strike rate to righties, and he threw it 53% of the time, but he doesn’t have elite velocity or extension on it, so the success was also about its ride away from righties. He certainly uses the pitch well, but it feels like a mediocre fastball that hitters will eventually catch up to. The only other offering he has to righties is a changeup, which certainly flashed at times, but he has an inconsistent feel for it, which makes it hard for me to believe he can sustain strong production against MLB hitters relying primarily on that fastball.
He’s also a left-handed pitcher without a real swing-and-miss pitch to lefties. His slider has a sub-14% swinging strike rate, which means he’s AGAIN relying on the four-seamer that he throws over 58% of the time to lefties. I know the SIERA calculations see above-average swinging strike rates and Stuff+ grades, but when I look at his pitch mix I don’t see a path for that to repeat itself unless he adds more bite to his slider or finds more consistent command of his changeup. Pair that with his unclear rotation spot, and he’s just a late-round dart throw for me.
Brayan Bello – Boston Red Sox
I have also written about Bello three times this off-season, but I truly believe this is the year Brayan Bello breaks out. Yes, I did say that last year but this year feels a bit different. For starters, Bello tweaked his slider into more of a sweeper at the end of 2023, then spent most of the offseason working on it, and it graded out as an above-average pitch by PLV in 2024. He also threw the slider nearly 40% of the time to righties after throwing it 22% to righties in 2023, which shows us his increasing trust in the pitch. The swinging strike rate on it jumped from 10% in 2023 to 16% last year, and the strike rate went from 54% to 62%, which makes it an average pitch from a command sense. Additionally, the command of the pitch got even better as 2024 went on. From July 1st on, he had a 66% strike rate and a 24.1% K-BB% on it, and the pitch also had a 24% PutAway rate on the season, so it was a good two-strike offering for him. Yes, the slider gives up a higher ICR than we’d like and that led to a 25% HR/FB rate, but it was his first full year throwing the pitch so we should expect improvements in 2025.
So Bello with a good slider was supposed to be a game-changer for him, right? Well, the issue is that as his slider got better, he seemed to lose the feel for his change-up, which has always been his best pitch. Even though he doesn’t throw the changeup often to righties, Bello’s command of the pitch suffered in 2024, with a lower zone and strike rate and it got hit much harder. It still had an 18.5% swinging strike rate to lefties, which means it remains an elite swing-and-miss pitch to opposite-handed hitters, but Bello really needs it to be a strike pitch to righties to complete his arsenal.
The thing is, it always had been that pitch for him, so why can’t we expect it to be that way again? We’ve heard plenty of pitchers mention that the second year they throw a new pitch is usually the year where things start to click a little more because they can often lose feel for a pitch in the middle of the season or spend so much time focusing on the new pitch that they lose feel for an old pitch. As a result, it makes sense to think that Bello’s arsenal will be a bit sharper in 2025. As it stands now, Bello checks the boxes that we want to see in a strong starting pitcher with a fastball for strikes and secondary for whiffs to hitters of each handedness. If he can get the command of his changeup back to be a consistent strike pitch then he has all the things I want from a starting pitcher and we could see a big leap.
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