Starting Pitcher SIERA Underperformers & Overperformers — May 5, 2026

Out of all the ERA estimator equations we have, SIERA does the best job at predicting future ERA. That said, they all kind of stink because luck is a meaningful factor here and it’s obviously impossible to predict the type of fortune a pitcher is going to have. Furthermore, underlying skills often change, whether it’s added or reduced velocity driving strikeout rate changes or a pitcher suddenly learning control and improving his walk rate dramatically. So for the ERA equation to be right, it requires the common “all else being equal” caveat that demands that the underlying skills to the same, and that doesn’t always happen.

We’re still in small innings sample territory which means ERA itself is almost totally meaningless. But that doesn’t mean it’s easy to ignore and your leaguemate(s) might be weighing that figure staring them in the face far too heavily. That’s why this early, it’s much better to stick with SIERA (and Stuff+, Pitching+, K%-BB%, etc).

So let’s start with the SIERA underperformers to see if we could identify any strong trade targets.

Before diving into the specific players, you might notice that many of these pitchers haven’t actually pitch well at all, even though they have massively underperformed. So for those that still sport high 4.00-5.00+ SIERA marks, I’ll only discuss a handful.

Gosh, I was really excited about a Kodai Senga rebound after he got demoted last year, as he was throwing harder in spring training. That velocity spike carried into the regular season, but then it dipped, dipped again, and by his final start before hitting the IL, he was barely higher than last year. With poor control, I like him much more averaging 97 MPH with his fastball than 95 MPH.

Okay, so perhaps some of Matthew Boyd’s inflated .377 BABIP (which is partially inflating his ERA) is due to the 23.8% LD%, and all those hits falling in is crushing his LOB% as well. But with a career 19.6% LD%, there’s no reason to think he’s suddenly unable to avoid line drives. His strikeout rate has skyrocketed to 31%, fueled by a career best 14.2% swinging strike rate. That sounds great and it’s what’s leading to the sparkling SIERA. But rather than accept that at face value and rush out to pick him up, you need to ask yourself whether the strikeout rate itself is real. Even strikeout rates can be fluky!

His fastball velocity is down a bit from last year, but still in line, if not higher, than historically, while he has only marginally changed his pitch mix. Both his botStf and Stuff+ are below league average, with his botStf just a point higher than his career mark, while his Stuff+ is at exactly his career average. Both his Location+ and Pitching+ are at career bests and might help somewhat explain the high strikeout rate. Perhaps he’s just been putting his pitches in the perfect spot. That’s unlikely to continue.

Without clearly improved stuff or a pitch mix change, it’s hard to believe he could sustain anywhere close to this strikeout rate. His ERA should still certainly come down, but he’s no sub-3.00 ERA pitcher like SIERA is calculating now. I think the rest of season projections are fair so treat him like such a contributor.

Man, I wonder how long Garrett Crochet’s shoulder was hurting him. His velocity has been down a tick most of the season, so perhaps the injury is to blame. His strikeout rate has also tumbled, as has his SwStr% and CSW%, which is now below average. There has clearly been some bad fortune here, but this was obviously not the Crochet we all drafted. We’ll have to wait and see how he looks when he returns from the IL.

David Peterson’s underlying skills are almost identical to his last two seasons, and yet, his ERA has surged higher. He’s getting killed by a .371 BABIP despite the highest IFFB% he has ever recorded. The whole skills package is fine here, the high GB% really helps, but the low strikeout rate is a weakness. He’s definitely a hold in NL-Only and deep mixed leagues and still worth considering as a streamer in shallower formats.

Jesús Luzardo likely found his name on every buy low list as one of the most obvious candidates. He must have heard the frustration from his owners as he has now allowed just two runs in his last 13.1 innings. Once again, it’s been a BABIP problem, and once again, it’s partially deserved as he has allowed a 25.7% LD%. That shouldn’t last, but all those line drives did happen and definitely help explain the high BABIP, low LOB%, and high ERA. Other than that, everything else here looks fab, so there’s no reason to downgrade him any from your preseason expectation.

Wait, is this Aaron Nola from 2025 or 2026…because they seem to be the same! Last year, he posted a 6.01 ERA with a 3.81 SIERA. This year, he’s at a 6.03 ERA with a 3.84 SIERA. I don’t understand what happened here, but he’s suddenly got a BABIP problem that’s getting worse, and it’s made his already high HR/FB rate even more damaging. I thought last year his down velocity was a reason to avoid, but he still posted typical skills and the same is happening this year. I don’t know if the velocity dip is really the cause of such underperformance, it’s some extended poor fortune, or something else. His Location+ is easily a career low and below league average for the first time, so maybe he’s missing his spots and it’s getting hit? Given last year’s performance, I would be too afraid to try buying here, but I also would likely keep starting him if I already owned him.

Even though his SIERA is a poor 4.69, I still wanted to discuss Brandon Sproat. His sinker velocity is up nearly a mile per hour, while his four-seamer is up a bit less. He was a former top prospect, though he hasn’t actually pitched well in the minors since his time at High-A and Double-A in 2024. Last year, his Stuff+ sat at 107, so I had high hopes that the added velocity would lead to a breakout. Instead, his Stuff+ has dropped right to league average and his Location+ remains below average. He wasn’t good at Triple-A in 2025, so it’s hard to maintain any excitement here. Since he has to fix two things — both his ability to generate swings and misses and improve his control — I’m no longer interested.

Let’s now move on to the pitchers your leaguemates have picked up because of the shiny ERA, and yet despite the significantly higher SIERA, have continued to succeed.

Justin Wrobleski has just a 10.5% (not a typo) strikeout rate, but a .222 BABIP, no homers allowed, and an 86.5% LOB% has resulted in a microscopic 1.25 ERA. Oh, and he’s 5-0! Has he been picked up in your league? If so, immediately scan that owner’s team for underachievers and bombard them with trade offers.

Where did Chad Patrick’s strikeouts go?! Actually, he was probably very lucky to post the mid-20% mark he did last year given the weak 24.9% CSW%, so this might just be the world making things right over a two season span. With poor strikeout ability and a double digit walk rate, he should be nowhere near lineups.

I had no idea Nick Martinez had a 1.70 ERA. Heck, I had no idea he’s been a starter all season and has already made six starts! This is the exact same pitcher as last year when he posted a 4.45 ERA, but this version has benefited from a suppressed BABIP and crazy 91.5 LOB%. Pitching for the Rays is nice, but with limited strikeout ability, there’s no downside protection when he stops standing nearly all his baserunners.

Alright, so unlike the first three names, there’s some intrigue with Spencer Arrighetti. At least his strikeout rate sits in the mid-20% range and he’s posted a 29.8% CSW%, which is excellent. What’s interesting here is he’s an example of where the stuff models disagree — his botStf is a fantastic 58 (50 is average), but his Stuff+ is actually a below average 98. Both do agree his control/command is below average, though, and that’s to be expected given his consistent double digit walk rates. That has been the one big weakness in his career so far, but it hasn’t made a lick of a difference this year. He can thank his low HR/FB rate and high LOB% for keeping his ERA just below 2.00. I bet there’s someone in your league that thinks this is his breakout season, so go find that owner!

Depending on your league rules, the Shohei Ohtani owner might not care about his pitching if he’s only one player. For those who do care about his pitching, it’s been another strong year, but obviously he’s no sub-1.00 ERA guy…no one is. I don’t think there’s anything to do here for his owners since no one is paying a sub-1.00 ERA price.

Ughhhh, José Soriano always intrigued me, but the promise of a poor Angels defense behind the extreme ground ball pitcher, to go along with an underwhelming strikeout rate, was enough to not bother speculating this year. OOPS! Like Ohtani, obviously he’s not a sub-1.00 ERA guy. But with a 30.1% strikeout rate, driven by a SwStr% surge, and a 3.22 SIERA, this has still been a breakout. Pinpointing what’s fueling the breakout is tough. He has thrown his sinker less and upped his four-seamer and splitter usage, which should have reduced his GB% (it has) and increased his strikeout rate (it has). But I wouldn’t expect these changes to increase his strikeout rate by nearly ten percentage points!

His Stuff+ is identical to last year, which is below both his 2023 and 2024 marks, though his Location+ is up a little (and it’s actually been above average for three seasons now, which is surprising given the below average walk rates). So I’m really not sure what else could be leading to the breakout, but the results have obviously been there and he’s generating swinging strikes like never before. It couldn’t hurt to see what you could get for him, but I don’t think he has the name value or former prospect status to believe selling high would be worthwhile.

Clay Holmes is almost exactly the same pitcher as last year, but somehow even with all those grounders, he’s allowed just a .210 BABIP. Oh, and he’s stranded 90.2% of baserunners. The high GB% gives him a floor and prevents implosions, but the lack of strikeouts and expected unappealing WHIP is problematic. Like Soriano, I doubt he’ll command much in return, and if I was an owner, I’d likely just keep starting him since he should remain a solid pitcher even with regression.

Boy, what a difference one season makes! Bryce Elder went from middling underlying skills and a 5.30 ERA to middling underlying skills and a 1.88 ERA. Incredibly, his xERA is just 2.98, so he has truly excelled at limiting the quality of contact against him. However, that doesn’t mean he’ll continue to, especially since he’s never done so historically. With well below average stuff (85 Stuff+), I’m selling high if at all possible, which probably isn’t, so I wouldn’t even bother with him in anything other than an NL-Only league.

Noah Schultz was a big free agent add when he was recalled earlier this season and from the surface, it looks like he was well worth the FAAB money. But that’s solely due to a .173 BABIP and 4.5% HR/FB rate. His Stuff+ is right at the 100 league average, with his strikeout and walk rates right in line with what he posted in the minors in 2025. He’s a major WHIP risk.

Eduardo Rodriguez is good again? Nah, this actually might be one of the worst versions we’ve seen of him, as both his strikeout and walk rates are at career worsts. I’d be nervous owning him in an NL-Only league given the tiny 6% SwStr%.

Foster Griffin spent three years in NPB after recording just eight innings in MLB. He posted some solid skills there, but those predictably have taken a bit of a hit back with the Nationals. His pitch mix has completely changed from when he was last here, but his Stuff+ is below average and he’s getting by thanks to a .220 BABIP and high LOB%. He’ll probably end up back in free agency within the next couple of weeks in any leagues he was picked up in thanks to his strong ERA.

For the full list of SIERA underperformers and overperformers, plus a plethora of additional metrics for both pitchers and batters updated weekly, visit ProjectingX.com to learn more about and subscribe to ProjectingX IQ.