A month ago, one of the biggest issues surrounding the Diamondbacks was their #4 starter not playing as well as he should have. Corbin has extended runs of success and failure, which hasn’t been just a 2017 thing, it’s been a thing for most of his MLB career. In his first 6 starts, Corbin pitched to a 2.29 ERA with a 30/11 K/BB and an average Game Score of 56. In his next 6 starts, Corbin pitched to a 9.00 ERA with a 24/9 K/BB with an average Game Score of 28. In his last 8 starts, Corbin has pitched to a 3.08 ERA and a 53/12 K/BB and an average Game Score of 56.
A month ago, the majority of the Snake Pit was willing to jettison Corbin from the rotation and throw a total unknown or wear out Delgado in his place. The issue with replacing Corbin in the rotation was there were no realistic options. Fortunately the Dbacks have a good manager and was willing to let Corbin figure things out because he really didn’t have any other choice. Fortunately, that issue has resolved itself.
In Corbin’s last 8 starts, he hasn’t given up more than 3 ER. BABIP is still an issue as Corbin has given up 53 hits in his last 47 1⁄3 innings, but I don’t think opponents will keep up a .366 BABIP against him. However, the peripherals are very encouraging as Corbin’s strikeout rate has jumped to 26.9% and a decent walk rate of 6.9%. Even though he’s giving up hits, limiting free passes and keeping the ball in the yard has limited the amount of runs. There are still reasons to believe Corbin can still get better because his season BABIP is .345 and HR/FB rate is 16.8%, both much higher than his career averages.
So what’s been behind the recent run of success? The answer is a change-up that has finally developed into a useful pitch. From June 8 to July 15, Corbin’s change-up has produced strong results. Over that time period, opponents are hitting .222 with a .278 slugging percentage and a 10.27% whiff rate. The pitch is generating ground balls just a bit under half the time as well although it also yields a 40% line drive rate, but that won’t sustain over a large enough sample size. Corbin uses his change-up about 15-20% of the time in his starts, so it’s used enough as a change of pace weapon against RHH.
The success hasn’t manifested completely in terms of batter productivity, as RHH have a .346 wOBA against him, but the damage hasn’t happened against the change-up as they’re hitting .250 with a .313 SLG. The damage has mostly happened against his 4-seam and 2-seam fastballs. So Corbin has gone more to mixing things up as he isn’t throwing any single pitch more than 30% (slider) and using his change-up 16% of the time. So not only is the change-up developed into a reliable 3rd pitch, he’s been also mixing things up more against RHH. The results speak for themselves as Corbin has a 3.08 ERA since June 8th.
For the last couple seasons, the Dbacks have needed Patrick Corbin to develop into a consistent starter to deepen the rotation. After mightily struggling last year, Corbin may have put those struggles behind him now. That’s a huge boost to the Diamondbacks playoff chances with their #4 starter able to finally show signs he can be counted upon down the stretch.
*All stats pulled from Fangraphs and Brooks Baseball.