2016 RoS Starting Pitcher Strikeout Rate Surgers by Mike Podhorzer July 25, 2016 Let’s do one final rest of season xK% update. If you recall, my xK% equation uses Baseball-Reference.com metrics to calculate a pitcher expected strikeout rate. It’s missing a sequencing component, though who knows if that’s even a skill. But even without accounting for such, it has proven to be one of the best expected metrics we have developed, at least by R-squared. So let’s begin with the fantasy relevant starting pitchers whose expected strikeout rates are well above their actual marks, suggesting significant upside over the rest of the season. Potential Strikeout Rate Surgers Player Str% L/Str S/Str F/Str K% xK% K%-xK% Mike Foltynewicz 66.4% 29.8% 16.1% 28.2% 21.6% 24.5% -2.9% Jordan Zimmermann 67.3% 27.6% 12.4% 28.8% 15.2% 17.3% -2.1% Nathan Eovaldi 65.0% 28.0% 15.8% 27.1% 18.6% 20.6% -2.0% Steven Wright 63.2% 29.2% 18.4% 23.5% 20.3% 22.1% -1.8% Matt Moore 65.1% 27.2% 17.0% 27.3% 19.9% 21.7% -1.8% League Average 63.8% 26.6% 17.2% 27.7% My apologies for this being the most boring list of pitchers I could have dreamed of. Just a week ago, Jeff Sullivan dove into Mike Foltynewicz‘ newfound ability to get ahead in the count. But who knew he also may be in for a nice uptick in strikeout rate?! Though he throws in the mid-90s on average and has nearly hit 100 this season, Folty has never really had the gigantic strikeout rates you might expect from someone with his fastball. That’s because his slider isn’t very good, generating a well below average SwStk%, while his curve has just been fine. You could see that his S/Str (swinging strike rate) is actually below average, but his strong xK% comes from above average marks everywhere else, including lots of strikes thrown. It’s a lot to ask for a pitch to improve their secondary pitches, but Folty already has the fastball and the improved control, so the light could turn on at any moment. Even if it doesn’t, xK% thinks he should be striking out even more hitters right now. Jordan Zimmermann has seen his strikeout evaporate after moving to the American League and while strikeout rates typically do fall, Zimmermann’s has been far more precipitous than the average pitcher has endured. That said, he’s still inducing looking and foul strikes at a better than average clip, while throwing tons of strikes. It certainly doesn’t fully make up for his complete lack of swings and misses generated, but xK% does think he should be punching out more batters. That said, even if his strikeout rate does rise a bit upon his return from the DL, it might not move the ERA needle as he’s sure to start giving up more home runs. All that strikeout rate jump will do is prevent his ERA from spiking toward his ugly SIERA. Hey, look at that, Nathan Eovaldi has only allowed three earned runs in his last two starts. If we thought Foltynewicz’ strikeout rate didn’t quite match his high octane fastball, Eovaldi has been even more curious throughout his career. His strikeout rate is already at a career high, but xK% suggests things could improve even further. The odd thing about his season is he has typically had BABIP issues, but at the moment, he hasn’t. Instead, he’s battling HR/FB rate problems, something he has never dealt with previously. In fact, he had never posted a HR/FB rate aboev 8.1% in his entire career, and this year it’s at 19%! Fun fact — he hasn’t induced even one swing and miss on his curve ball this year, out of 82 thrown. Yikes! Steven Wright has already shocked us all with his performance and yet xK% thinks his strikeout rate should actually be a touch higher. He has induced lots of swinging and looking strikes, not so much the foul variety. And while knuckleballers don’t usually follow the rules, you have to believe his 5.7% HR/FB rate is headed upward. The .263 BABIP, perhaps not, which means he’ll definitely beat his SIERA and ZiPS and Steamer RoS projections. But I still don’t really want a piece of him over the rest of the season. I have continuously defended Matt Moore when he was toting a 5.04 ERA through his June 24th start, as he was suffering from those familiar inflated BABIP and HR/FB rates. Since, his luck has finally turned around, as he has posted a 2.38 ERA over five starts. Interestingly, his skills have actually reversed course and his SIERA during that period sits at a robust 5.36! You can thank a strikeout rate that has collapsed, but saved by a .204 BABIP. I think his turnaround is complete and he’s now at where he should be at. His xK% suggests a bit of strikeout rate upside, but he has been an extreme fly ball pitcher recently, which means lots of home runs. He’s nothing more than a streamer in shallow mixed leagues and I’m not particularly interested in buying anymore in deeper formats.