Corbin was a rockstar in 2018. To explain his semi-miraculous metamorphosis, let’s look at three metrics: home run rate, strikeout rate, and pitch usage.
From 2016 – his first full season post-Tommy-John – to 2018, Corbin’s HR/FB fell from 18.3% to 15.3% to 11.1%. Translation: his home runs per nine innings went from 1.39 to 1.23 to 0.68. No matter how you slice it, that’s a marked improvement.
Interestingly, 11.1% HR/FB is still pretty bad! Additionally, HR/FB is not park adjusted: Chase Field had the second highest HR park factor in 2016 (1.292), fourth in 2017 (1.222), and….will ya look at that: 19th in 2018 (0.955). I guess the humidor is working.
The humidor helps, but it’s moot when the hitter swings and misses. Suddenly in 2018, Corbin became a swing-and-miss pitcher. Corbin’s K/9 in each season since 2012: 7.23, 7.69, 6.06, 8.26, 7.57, 8.45, 11.07.
What the heck happened in 2018? That low number, 6.06, was 2015, his first year back from Tommy John – makes sense – but that’s a pretty righteous jump to 11.07 this season after never clearing 9.0 in any of the six prior seasons.
Corbin’s rate metric jumped, but so did the volume; Corbin tallied 246 strikeouts, easily topping his previous career high of 178 in 2013 and 2017.
So how did – at the age of 29 – Patrick Corbin transform from Wade Miley into Curt Schilling (whom Corbin passed for third on the Dbacks all-time strikeouts leaderboard!)? There’s probably not any individual factor that accounts for the hike in K-rate, but take a look at his pitch usage rates over his career versus 2018:
Fastball career: 28.6%, 2018: 19.7%
Changeup career: 7.9%, 2018: 1.2%
Sinker career: 31.2%, 2018: 28.8%
Slider career: 30.5%, 2018: 41.2%
Curveball career: 1.9%, 2018: 8.8%
Prior to 2018, Corbin’s career curveball rate was 0.0%: he never threw a curveball before. Essentially, he replaced his changeup with a curve, but more broadly, he shifted wholesale towards more breaking stuff.
He remains primarily a fastball-sinker-slider guy, but he leaned much more heavily on movement in 2018. He threw his sinker less often than his career average, but his career rate is skewed by exceptionally high usage in 2012 (40.6%) and 2013 (43.6%).
The changeup was more-or-less eradicated from his arsenal, while fastball usage (19.7%) decreased from 2017 (30.2%), which decreased from 2016 (40.1%).
Corbin’s metamorphosis didn’t happen overnight; it took three seasons of weaning himself off the fastball, while increasing dependence on movement: sinkers, sliders, and now, a curveball.
Further bolstering this new approach was the exceptional utility of his slider. Per Fangraphs, Corbin’s slider was the most effective in the league by a fair margin. The right mix of pitches can transform a pitcher, but so can the right pitch.
Or maybe it was the humidor. Regardless, kudos on a great 2018.