Starting Pitcher SIERA Underperformers — 5/3/2022

With qualified starting pitchers having made four or five starts, it’s the perfect time to start comparing ERA to SIERA marks. While ERA stares us all in the face and could cause panic when it’s significantly higher than expected or excitement when it’s far lower, it’s not all that meaningful over a small sample. Instead, we should be focused almost solely on the underlying skills, and mostly ignore the actual results. Luckily, we have a metric that accounts for these underlying skills and calculates an estimated ERA based on those skills — SIERA. It’s all I look at over the first few months of the season. Heck, I’m not sure there’s a time at all during the season where I choose to use ERA instead of SIERA! So with that in mind, let’s first review the qualified starting pitchers that have most underperformed their SIERA marks. Do any of these names make for good trade targets? Let’s find out.

Tyler Mahle broke out during the shortened 2020 season and followed that performance strongly over a full 2021 season. This year, his strikeout rate has tumbled, walk rate spiked, and ERA skyrocketed. From his “luck” metrics, it’s pretty clear that an astronomical BABIP and suppressed LOB% are inflating his ERA. Of course, he hasn’t allowed a homer yet, which is offsetting the bad luck right now. From a pitch mix perspective, he has changed things up. He has replacement a significant portion of his cutter usage for a slider and also upped his splitter usage. The slider has generated the highest SwStk% of any of his pitches and his overall SwStk% is in line with last year, but down from 2020. Oddly, his CSW%, while down slightly over the past two seasons, hasn’t dropped as much as his strikeout rate has, suggesting he’s been a bit unlucky on the strikeout rate front. His fastball velocity is down a bit, but not enough to ring the alarm bells. I don’t see any glaring issues here and figure he’ll revert back to a low-4.00 ERA over the rest of the way.

Mitch Keller has maintained the increased velocity so far and he actually recorded his highest ever game velocity in his last start at 97 MPH. Unfortunately, it’s done nothing really for his strikeout rate or his SwStk%. He has also suffered from inflated BABIP and HR/FB rates compared to league average, both of which have pushed down his LOB%. Overall though, his skills have been good as that 3.52 SIERA attests. I still expected more from this velocity spike, but there’s been clear improvement between the walk rate and GB% surge. I’m still holding in my 12-team mixed league.

Again, Aaron Nola?! Last year, he was one of the biggest SIERA underperformers, and he has continued that trend over his first 27.2 innings this season. His skills have surged to career bests, but a HR/FB rate that has jumped over 20% has hidden them. I wouldn’t expect the skills surge to last, especially with down velocity, but his ERA should certainly improve.

Marcus Stroman has been the same as always in terms of underlying skills, though his SwStk% has plummeted, but offset by an increased CStr%. However, his LOB% has oddly cratered, which is what has inflated his ERA. He’s not exciting given the pedestrian strikeout rate, but he should get his ratios back to normal moving forward.

Eduardo Rodriguez’s start is actually concerning. Sure, he’s been insanely unlucky given that crazy 38.2% LOB%. However, his strikeout rate has dropped and his SwStk% has completely plummeted. His velocity and pitch mix are relatively stable, but shockingly every pitch’s SwStk% is in single digits. His changeup has been his best whiff pitch, recording an 18% SwStk% over his career, so it’s crazy to see that at just 9.7% right now, and his fourseamer at less than half its career mark. I don’t know what’s going on here, but I would be too nervous to try trading for him.

HA, so the Rays lose Tyler Glasnow for a year and just replace him with Shane McClanahan. It’s absurd to think he’s one of the unluckiest pitchers given his ERA is already a strong 3.00. But check out that insane HR/FB rate! That will obviously come down as the sample size of his fly ball total rises. Of course, it’s hard to believe he could sustain this strikeout rate all season, but it’s pretty clear he’s going to be elite in however many innings he can throw.

Frankie Montas’s skills are virtually unchanged from last year, and while his BABIP has been low, his HR/FB rate has risen back up to his 2020 level, and his LOB% has plummeted. The LOB% should get sorted out and his ERA should quickly drop back into the 3.00 range.

It’s surprising to see Kyle Freeland with a sub-4.00 SIERA given that his home park hampers his underlying skills. He’s taken his SwStk% into double digits for the first time, but that hasn’t boosted his strikeout rate. Even though he’s on this list, I would want no part of him. The Coors factor, plus the low strikeout rate, means he’s an NL-Only guy, and even in that format, I would prefer a middle reliever.

It’s been quite the reversal for Kyle Hendricks, who had consistently outperformed his underlying skills, despite a low velocity fastball and below average strikeout rate. Has the magic worn off? His BABIP has now remained worse than league average, so it’s very possible that he has lost whatever it was he had when consistently posting better than league average BABIP marks. His walk rate has also surprisingly taken a hit and sits nearly double his career average. One of the keys to his success had been pinpoint control, so without that, he’s makes for a scary start. Buying him now requires the expectation he gets his BABIP and LOB% mojo back and that’s not something I’m willing to bet on.