Starting Pitcher SIERA Underperformers — Through June 5, 2023

Two months into the season is a good time to evaluate your team, its strengths and weaknesses. You usually can never have enough pitching, as there’s always someone who gets injured, suddenly loses velocity or effectiveness, and then you’re scrambling. So let’s review the starting pitchers that have underperformed their SIERA marks the most so far. This could be a good target list to trade for that includes pitchers that shouldn’t cost much to acquire.

This time, I didn’t just copy and paste the top six underperformers, as the majority still had weak SIERA marks. In other words, it’s nice to know a pitcher has underperformed his SIERA by 1.50 runs, but if his ERA is 6.00 and SIERA is 4.50, you probably still don’t want him on your team!

It is really surprising to find Lance Lynn atop this list, as he has regularly overperformed his SIERA in the past. This year, his BABIP has skyrocketed to the second highest mark of his career, his HR/FB rate has surged to a career worst, while his LOB% has plummeted to a career low. All the while, his strikeout rate is normal, as is his CSW%, and while his walk rate is elevated compared to the recent past, it’s only marginally higher than his career average. His pitch mix is fairly similar to past years and his fastball velocity is down slightly, but not enough to raise any red flags. He has allowed his highest LD% since 2012, so clearly batters are hitting him, but it’s not clear why. Perhaps he’s just going through a short-term command rut. I’ve never been a fan of his skill set or owned him, so I’m not rushing to buy here. But I would imagine he improves dramatically the rest of the way.

While Tanner Houck’s HR/FB rate is above the league average, the bigger issue might be the lowly 61% LOB%. So a significantly higher rate of his baserunners end up scoring compared to league average. Much of LOB% in the short-term is luck based, so that’s gotta tick up. What I find both encouraging and odd is both his SwStk% and CSW% have increased compared to last year when he spent the majority of his time in the bullpen. That’s great, but the odd thing is that his strikeout rate has barely moved, and it remains well below what you would expect from that CSW%. It suggests some strikeout rate upside for sure. He looks like a nice target in deeper leagues.

Man, look at the BABIP that Clarke Schmidt has had to deal with! I expected to find a high LD% and/or few popups to explain the high BABIP, but neither of those have occurred. In fact, he has allowed a below average LD%. His strikeout rate looks pretty good, but keep in mind that his SwStk% is merely mediocre, as is his CSW%, so I would expect the strikeout rate to decline some if he doesn’t start inducing more swings and misses. Actually, I would make the bet that Houck posts a higher strikeout rate the rest of the way. Because I feel his strikeout rate falls, I don’t think his ERA will improve enough to get below 4.00 to come close to his SIERA, but he should still earn some deeper league value the rest of the way.

Poor Chris Sale and his owners, who are going to have to wait a while for his luck to turn around and ERA fall in line with his SIERA. While this clearly wasn’t vintage Sale, this was still an excellent pitcher, but he was victimized by worse than league average marks in all three luck metrics. Given his injury and return date up in the air, it doesn’t make much sense to target him in trade unless you’re giving up close to nothing.

Sadly, I’m losing my patience with Reid Detmers, who I own in two of my three leagues. His BABIP has jumped a full .100 points from last year, which has pushed his LOB% down more than ten percentage points. He has given up a high rate of line drives, which partially explains the high BABIP, but that’s something that should naturally decline with or without pitcher adjustments. And while his velocity has dipped a bit since his first two starts, he still remains well above where he sat last year. That has certainly boosted his SwStk% and strikeout rate, though I thought there could be some additional upside, especially given the near 14% SwStk%. I’ve lost confidence that this is the year of the big breakout, but he should definitely enjoy better results the rest of the season.

Pablo López is another who has enjoyed a velocity bump, but all it’s done is led to disappointment. However, his strikeout rate and SwStk% have both spiked to career bests. The weird thing here is none of his luck metrics look so out of the ordinary, and yet he has underperformed his SIERA by more than a run. What I like seeing here is an xERA right in line with his SIERA, suggesting that his batted ball quality, which is ignored by SIERA, fails to explain the gap between SIERA and ERA. Often times a pitcher will post a high BABIP or HR/FB rate, increasing the gap between SIERA and ERA, but xERA suggests it’s deserved given the quality of contact against. Here, xERA sees no such issues with contact against, giving me even more confidence that López’s results will dramatically improve the rest of the way.