In Trusting the Entire Body of Work: The April ERA Imploders

At the beginning of this week, I identified and discussed a group of hitters who suffered through miserable slumps at the beginning of the season, only to return to form, or better, the rest of the way. I then did the same for some of the players who enjoyed fantastic performances in April, just to regress back to what had always been expected the rest of the way. Though this was by no means an exhaustive study, the lesson for all these players is to trust their entire body of work, not the small sample of a month.

So let’s move on to pitchers. There performance jumps around even more, not only because they only make five to six starts a month, but also because a lot of their ultimate results is out of their control. So let’s revisit some of the worst April performers in ERA who bounced back big the rest of the way.

I had no idea that Mike Leake has posted a 3.39 ERA since the beginning of May. His strikeout rate hasn’t moved any, still sitting significantly below average, but his walk rate has been almost cut in half. Furthermore, his BABIP luck improved a bit, while his LOB% rebounded. His season SIERA stands just above his actual ERA, so he was likely very unlucky in April and the luck has balanced out. Still, with limited strikeout potential, he’s an AL-Only option only.

Does it surprise you that since April, Chris Archer has actually posted an ERA just below 4.00? Given his brutal performance with the Pirates so far (6.45 ERA), I would have guessed his ERA was North of 4.00 myself. The improved ERA is solely the result of reducing his BABIP from an absolutely terrifying .376, to a still scary .340, and remembering how to strand baserunners. His strikeout rate remains at its lowest since 2014 (despite the second highest SwStk% of his career), and his mark has actually declined since joining the Pirates. Call me crazy, but I’m buying him next year with a full season in the National League.

Vince Velasquez enjoyed a skills breakout in 2016, then regressed terribly last year before succumbing to injury. His skills have rebounded this year and were excellent through April, but an inflated BABIP and impossibly low LOB% conspired against him. Both of those marks improved markedly over the rest of the season, but oddly his walk rate skyrocketed, resulting in worse skills. Yet, his ERA sits in the mid-3.00s since April! Go figure.

Remember we were all freaking out about Zack Greinke’s down velocity during the spring? Welp, his fastball is averaging less than 90 mph for the first time in his career, and yet…it hasn’t mattered! Though he was still striking everyone out, a poor April coupled with the velocity loss kept me from trying to buy low. Oops. His strikeout and walk rates have actually regressed since April, but his BABIP has dropped too, while his LOB% has risen, causing his ERA to drop by two full runs. I’m still leery he’ll be able to maintain this level of performance given the sub-90 velocity.

So James Shields went from a solidly reliable guy to one of the worst pitchers in baseball in recent years. As a result, it was no surprise to see him open this season with a grotesque 6.14 ERA, and more walks than strikeouts. This from a guy who used to possess sterling control! Lucky for any owners brave enough to pick him up off the scrap heap, he hasn’t been quite as terrible since, as his strikeout rate has surged to at least an acceptable level, his control has improved, and his ERA has been much more palatable. He’s 36 though and like Greinke, has seen his fastball velocity fall below 90 mph for the first time. The end is near.

You all bought low on James Paxton after his 5.12 ERA finishing out April, right? RIGHT? Yes, he was walking too many, but it didn’t matter all that much given his above 30% strikeout rate. The walks return to normal after April and he enjoyed better BABIP and LOB% luck, pushing his ERA down to a level we had expected from the get-go. I love the guy, but his health is scary.

I warned you in February that Jose Quintana’s strikeout rate was on this ice, as my xK% equation suggested he was the luckiest starting pitcher in baseball last year on that front. And what do you know, his strikeout rate has tumbled right back to where it had been before last season. This coming even with a full season in the National League. He’s posted identically weak skills through April as he has over the rest of the season, but better BABIP and LOB% marks had made it look playable in nearly all leagues. With a SwStk% above 9% just once in his entire career, he’ll never end up on my roster.

We all know that Jameson Taillon added a slider, which he first threw with regularity in his last start of May. You see during the two time periods in the table above, his strikeout rate has barely budged since April. And guess what…even when adjusting his game log to begin on that last start, his strikeout rate has still been just 22.1%. So has the slider really aided his performance? It doesn’t appear so. It’s been all about the spike in LOB%, which merely means he’s stranded a whole lot more runners than he did through April. Because he throws 95 mph and his slider now sports a mid-teens SwStk%, I still hold out hope a strikeout rate surge is coming. Maybe he just needs to go to the Astros.