Starting Pitcher ERA vs xERA — Jun 4, 2024

It’s been nearly a month and a half since I last reviewed the starting pitchers who sported the greatest gap between their ERA and xERA marks. So let’s revisit these lists as they could provide you with a quick group of buy low and sell high candidates.

We’ll start with the xERA underperformers.

Too funny to see Reid Detmers underperforming his xERA the most and then being demoted to Triple-A on Saturday. Detmers posted an ERA pretty close to his xERA last year and an ERA below his xERA in 2022, so we can’t say he’s just a consistent underperformer doing (or not doing) something unaccounted for by the xERA equation. It’s really odd to see an inflated .333 BABIP, despite a strong/low LD%, FB% over 40%, and double digit IFFB%. A lot of his issues have come from a low rate of stranding runners, as he ranked second lowest among pitchers with at least 60 innings pitched. His velocity averaged a season low last time out, but the demotion seems like a severe overreaction to me. With a career best SwStk% and CSW%, the skills are fine, he just needed better defensive support and a rebound in his LOB%. He looks like a prime buy low in deep leagues.

Hunter Brown’s season line has been marred by a nine-run, two-thirds of an inning outing during his third start. The overall skills here are similar to last year, even down to the luck metrics all being worse than league average. It’s now been 210 innings over the past two seasons, and he sports an inflated BABIP, crazy high HR/FB rate, and worse than average LOB%. The first two are definitely pushing down his LOB%, so we can just focus on the high BABIP and HR/FB rates. As a ground ball pitcher who doesn’t generate many pop-ups, it makes sense to allow a high BABIP, but this high? Also, there’s little chance that high HR/FB rate is real. Remember, xERA accounts for his batted ball quality against, so it’s clear there’s a real sprinkling of bad fortune here. He’s been perfectly fine recently, but his overall line still looks terrible, so he could potentially be had cheap.

After last year’s strikeout rate spike to a career high mark, my only question about Pablo López was whether he could maintain the fastball velocity spike that fueled the surge. So far, the answer has been yes. His strikeout rate, SwStk%, and CSW% are all down marginally from last year, but still at the second highest rates of his career (minus the strikeout rate that’s a bit below his 2021 mark). Oh, and his walk rate is at a career low. Yet, his highest HR/FB rate since his 2018 debut, combined with his lowest LOB% since 2020, has crushed his ERA. One of the easiest buy lows there is.

Yeah, I don’t care how much Ryan Feltner might be underperforming, I don’t want a Rockies starter with a sub-20% strikeout rate anywhere near my roster!

Speaking of low strikeout rates, Ross Stripling was sporting a career low 13.9% mark before hitting the IL. I don’t think it needs stating that he doesn’t belong on your watch list.

Brandon Pfaadt’s underlying skills aren’t really all that different from last year, though his batted ball profile is significantly improved, featuring far less liners allowed, and far more pop-ups induced. It’s really surprising to find him underperforming given that his BABIP is better than average, and his HR/FB rate sits in the single digits. The culprit is the LOB%, where he sits at the bottom of the league as the only name below 60%. Just for reference, Jordan Lyles has posted the lowest LOB% among qualified starters over the past three seasons at 56.3%, but the second lowest was up at 66.4%. So it’s really, really hard to suffer from a mark this low all season long. I wish there were more strikeouts and whiffs here, as the results should improve some, but the skill set just doesn’t excite me.

Now let’s move on over to the overperformers.

How has Tyler Anderson managed a 12% swStk% and 27.2% CSW%, but only a 17.1% strikeout rate?! I have to think that rate improves, but it won’t be enough to prevent the major regression he’s due to suffer on his ratios. A .211 BABIP and 87% LOB% are just ridiculous. Give me a middle reliever over him in AL-Only leagues, as I can’t risk the impending implosion on my ratios.

Welp, Reynaldo López’s return to the starting rotation has gone far better than anyone expected! Incredible, he has matched his career high in CSW%, though his strikeout rate is a bit lower than you’d expect based on that mark. It’s pretty obvious what’s happening here — besides the better than average BABIP, which is something he’s done often in the past, he has also posted a microscopic 3.4% HR/FB rate, which simply ain’t going to last. Because of that low HR/FB rate and better than average BABIP, he has stranded over 80% of runners. It seems pretty clear that he has the skills to deliver positive value in shallow leagues, but his ERA isn’t staying this low for much longer!

Does Seth Lugo read FanGraphs?! As soon as I highlighted him in my last post and noted his shockingly low strikeout rate of 11.1% at the time, he has posted a 28.1% strikeout rate ever since. Crazy! All that’s done is bring his season rate up to around initial expectations, but perhaps those expectations should be raised? He still owns just a .251 BABIP, low 6.6% HR/FB rate, and league leading 89.5% LOB%, so high 20% strikeout rate or not, he’s benefited from some serious fortune. That said, with the strikeouts now, he clearly doesn’t seem like the most obvious sell high, though it never hurts to dangle someone like him just out of curiosity of your potential returns.

James Paxton has his strikeout count above his walk total now, which is weird to note, but important because that hasn’t always been the case this season. With his velocity down, he has managed to strike out just 14.2% of opposing batters, by far a career low and a shocking rate given his career 25.6% mark. Even scarier is his velocity notched a season line in his last outing. Depending on the quality of your leaguemates, you could either get something of value in return or get laughed out of the room no matter who you ask for. Might as well offer him around and see what happens…if you haven’t dropped him yet.

Logan Webb’s SwStk% is all the way down to a career low 7.6%, though he hasn’t been a big whiff guy historically. His velocity is fine and pitch mix similar to last year, so it’s odd to see. Like some of the others on this list, he’s been saved by a 6.1% HR/FB rate, which is unlikely to last, even playing half his games at Oracle Park. What’s really interesting here is the discrepancy between his SIERA and xERA. His 3.40 SIERA is in line with past years, matching his solid overall skills that are buoyed by a high GB%. On the other hand, his xERA is significantly higher, suggesting he’s given up a ton of quality contact, but hasn’t paid the price. I would personally choose to ignore the high xERA as nothing in his profile suggests cause for concern.

Jon Gray is finally enjoying the breakout season we all expected after departing Coors Field back in 2022?! No, not quite. His SwStk% is up, but strikeout rate right at his career average, as is his CSW%. As is the theme for many of these pitchers, his ERA has benefited from a tiny 3.3% HR/FB rate. He has allowed a double digit mark every year of his career since his first full season in 2016, so there’s absolutely no reason to think he suddenly learned how to keep his fly balls allowed in the park at a significantly better than league average rate. Oh, and his velocity is down to its lowest since 2020. It’s too bad he’s on the IL with a groin injury, as it makes it tougher to sell high here if anyone was willing to buy. Hope for a good first start back and then offer him around.