Starting Pitcher SIERA Underperformers & Overperformers — Jun 22, 2026

It’s been about a month and a half since I last checked on the starting pitcher SIERA underperformers and overperformers. So let’s revisit these names to find out if any make good trade targets or opportunities to sell high on.

We’ll start with the SIERA underperformers. I decided to limit this list to only those with SIERA marks of 4.20 and below since that’s around the league average ERA and SIERA. There’s no sense in seeing a guy with a 7.00 ERA underperforming his 5.00 SIERA on here.

When I last published this list, Aaron Nola ranked ninth, but I didn’t filter for SIERA marks of 4.20 and below. With that filter in place, he would have ranked as the fifth largest difference. While it would seem he has gone backwards, his differential is a bit smaller, and his ERA has improved from 6.03 to 5.71! Okay, so that’s barely an improvement, which is disappointing given how high his baseline was. What’s crazy is that he massively underperformed last year too, in a very similar fashion to what he’s done so far this year. What’s been killing him is a combination of all three “luck” metrics, with an inflated BABIP (the second highest of his career), a high HR/FB rate, though he’s suffered from such an issue often, and a low LOB%, which is below his career mark. His fastball velocity has rebounded somewhat from last year’s trough, and his xERA is only slightly higher than his SIERA, so even his contact quality suggests he’s deserving of better results. Still, with about 170 innings of near-6.00 ERA ball these past two seasons, it’s hard to bank on a rebound. Maybe in a deep league if you’re already hurting in ratios, he’s worth speculating on since you have less to lose.

David Peterson had another poor performance yesterday, the day I’m typing this, though I’m not sure if it would widen the ERA-SIERA gap (it probably would slightly). His underlying skills are quite similar to the previous two seasons, when he posted much better ERA marks, though the skills themselves are underwhelming. The strikeout rate drop he suffered from in 2023 has not recovered. He has been victimized by a hefty BABIP and a super low LOB%, the latter of which almost has to increase some. Still, with a poor strikeout rate and an offense that ranks 28th in wRC+ backing him, the upside here is clearly not very high. Unlike Nola, xERA suggests Peterson deserves a lot of the blame for his inflated BABIP.

Like Peterson, Emmet Sheehan also pitched poorly yesterday, but his SIERA is also going up after striking out just 19% of batters and walking 14% of them. Coming into the season, he was a popular breakout pick, but the results have not been there. Incredibly, the underlying skills have actually been quite good, but an inflated HR/FB rate has mostly been the culprit to his high ERA. His sub-4.00 xERA is only a bit higher than his SIERA, so there appears to be loads of rebound potential here. While his fastball velocity is down on the year, it’s been stronger his last three starts, though back to his season average in his start yesterday. His Stuff has also rebounded, as his Stuff+ has been at least 101 for six straight starts (excluding yesterday since it hasn’t been calculated as of this typing), after opening the year with sub-100 Stuff+ marks over his first seven starts. He looks like a great trade target, and might come cheaper than ever after this last drubbing.

Jake Irvin was enjoying a skills breakout before a shoulder injury landed him on the IL. It’s anyone’s guess how he’ll recover when he eventually returns.

A fortunate ERA masked a clear skills degradation last year for Luis Castillo, and now the pendulum has swung too far the other way. His SIERA is similar thna last year, but his BABIP has jumped back above .300, while his LOB% has dropped to an impossibly low sub-60% mark. Without the strikeout upside of years past, there’s far less upside, and with the Mariners piggyback rotation, his future is quite cloudy. It all adds up to a guy whose ERA is likely to improve some, but might not lead to a whole lot of fantasy value anyway.

Sean Manaea opened the year in a bullpen role with a fastball that failed to average 90 MPH until his sixth outing. With the exception of his final relief appearance before moving to a traditional starting role, he has averaged 90+ MPH ever since. With his velocity mostly fixed, he looks far less risky. While his HR/FB rate sits at a career low, it’s been offset by a career high BABIP and a sub-70% LOB% below his career average. I like him better than Peterson and is a streaming option in most shallower formats.

So much for Roki Sasaki turning the corner! After a brilliant seven shutout inning outing with 10 strikeouts, he follows it up with a dud that included seven runs allowed in just 4.1 innings. On the year, though, the skills are significantly improved from last season, but his ERA is up. It’s still very difficult to guess how he’ll produce the rest of the way, but he’s clearly better now than he has been and is a much smarter risk with the strikeouts up and walks down.

Jesús Luzardo was one of the biggest names on the original list. Back then, he was sitting with an unsightly 5.09 ERA, but an elite 2.71 SIERA. Now, his ERA is down to 4.20, but his SIERA has jumped to 3.40. That SIERA mark is a perfect match from last year while his ERA is only up a bit. His strikeout rate has declined, so his underlying skills aren’t jumping out of the page like they were, but it hasn’t mattered since his luck has turned around. Obviously, there’s little chance you could acquire him at a discount at this point, and owners might get continued ERA improvement from here.

Finally, the velocity bump Ryan Weathers first experienced in 2024 has translated into a big strikeout rate spike. Oddly, his SwStr% is actually down from last year and in line with 2024, as it’s been his CStr% that has surged. What’s killed him so far is an 18.6% HR/FB rate, which has offset a low BABIP and high LOB%. He has always struggled with HR/FB rate, so it’s very possible that whatever he’s doing is making him homer prone, despite the low BABIP. Sure enough, a quick check of his Statcast profile shows us an 11.6% Barrel% allowed, which would be a strong rate for a hitter, which is not great coming from a pitcher. It’s why his xERA is basically in line with his ERA and significantly higher than his ERA. At some point, Max Fried is going to return and if the Yankees rotation is healthy at that time, the team will have a decision to make and depending on how Weathers pitches, could render him the odd man out. That makes him tough to trade for, but he’s worth starting weekly for now.

Now let’s flip over to the overperformers.

Well these names seem far less exciting than the underperformers!

Eduardo Rodriguez ranked 12th on the original list and now he’s first, as his ERA has actually improved, while his SIERA has only dropped marginally, and remains near 5.00. How the heck is he doing this was a career worst 17.9% strikeout rate?! It’s magic baby! Not only is his strikeout rate a career worst, but his walk rate is at a career high. With career worst strikeout and walk rates, you might think his ERA is sitting near 6.00, not closer to 2.00. Even his xERA is 4.93, which is higher than his SIERA, so no one could argue he has “kept hitters off-balance” or induced soft contact, as his Soft% ranks 47th out of 66 qualified pitchers. He’s done it with a combination of a .256 BABIP, the lowest of his career, and an impossibly high 86.1% LOB%, which ranks second highest among qualified pitchers. I keep seeing fantasy owners in my leagues stream him, which is mind-boggling given the poor skills. Starting him for any given game seems to be playing with fire, as literally nothing in his profile suggest he’s a good pitcher right now. So far, it’s worked out, but why would you expect it to continue?

It’s been a breakout so far for rookie Walbert Ureña, who I was intrigued by during spring training, but avoided given his low strikeout rates and high walk rates in the minors. He has carried over that skill set in the Majors so far, and while I love the GB%, he’s been doing this with smoke and mirrors. With a 97+ MPH four-seamer and sinker, you might expect more strikeouts, but perhaps they come eventually. For now, he walks too many given the below average strikeout rate, and has needed a low BABIP and high LOB% to maintain the sub-3.00 ERA. A 3.25 xERA actually suggests he is deserving of a lot of that low ERA, most likely a result of a superb 15.1% LD%, which is great, but unlikely to be sustainable over the rest of the season. What’s funny is how similar his skill set is to his rotation mate José Soriano. I do like the foundation here and would bet on a skills-backed breakout in the future, but for now, there’s some serious regression to be had in that ERA.

Nick Martinez ranked third on the last overperformers list, and obviously his ERA has risen from 1.70, but the regression hasn’t been enough. In fact, his SIERA has gotten a been worst since. With just a 15.1% strikeout rate after yesterday’s performance, there’s no cushion for when his ERA jumps to meet his SIERA. He’s gotten by thanks to the combo of a single digit HR/FB rate and LOB% over 80%, and while he’s recorded single digit HR/FB rates in the past, his career LOB% is only slightly above the league average. Without any semblance of strikeout potential, I would be nervous ever starting him, as any given game could be a hit barrage against.

Shohei Ohtani is the first pitcher on this list who has been legitimately good, but obviously not 1.47 ERA good. His strikeout rate is at a career low, and he’s benefited from good fortune in all three luck metrics, with tiny BABIP and HR/FB rates and a LOB% over 80%. If he’s one player in your league, you can’t trade him, but if you own the pitcher version, he might be a good name to offer as he’s only pitched more than 132 innings once.

The top name on last month’s list was Justin Wrobleski, whose ERA has predictably risen, but still stands below 3.00. More impressive though is that his skills have improved, with his SIERA declining from a ghastly 5.39 to 4.53. While his strikeout rate jumped to 19.1% in May, it’s back down to just 15.2% in June, though he has continued to reduce his walk rate. Without any real strikeout potential, he essentially looks like a Martinez clone from above, though with a better team backing him. I still wouldn’t want to be starting him in any leagues.

Add Brandon Young to the list of names with low strikeout rates that are overperforming. He recorded strong results again yesterday, which will likely improve his SIERA, but with only one run allowed, might still increase the gap. Despite a below average LOB%, a low BABIP and HR/FB rate have been enough to keep his ERA near 3.00. He posted a 6.24 ERA last year with slightly better skills, so it’s anyone’s guess who he made a pact with to get significantly better results this year. Sell, sell, sell.

Ben Brown’s stats include his time as a reliever, but his gap actually doesn’t differ much when just isolating his starts. As a starter, he has posted a microscopic 1.70 ERA versus a 3.61 SIERA, so he has still been excellent as a member of the rotation, but clearly not sub-2.00 ERA excellent. As usual, the gap is driven by a low .239 BABIP, miniscule 2.5% HR/FB rate, and inflated 82.9% LOB%, so there’s no chance the low ERA is sticking. But he’s still been darn good and has actually posted a higher strikeout rate as a starter this year than reliever, which is surprising. I would still dangle him just to see what you might be able to get, but he’s not an urgent sell like some other names on the list.