After Charlie Morton’s first three starts of the season, his ERA stood at 1.64, and I noted that his revamped style of pitching simply wouldn’t let him keep this up for much longer. Since I wrote that article, Morton has made five more starts and posted an ERA of 3.27 – technically that does represent regression, but it’s still better than I would have expected. After another dominant start last night, I figured we needed to take another look at the guy they call Ground Chuck.
In Morton’s last five starts, he has reduced his reliance on his sinker, going from 90% fastballs in his first three starts to “just” 80% in his last five. He’s still basically just throwing one pitch, but he has mixed in his off-speed stuff a bit more in order to be a little less predictable. It has helped as well, as after posting a 12/6 BB/K ratio in his first three starts, he’s at 14/23 in his last five. The decrease in fastball usage has led to fewer walks and fewer ground balls, but overall it’s been a worthwhile trade-off for Morton – his xFIP has dropped from 4.09 in April to 3.63 in May- putting fewer men on base outweighs the small change in his batted ball profile.
But there’s still an area that has to be cause for concern with Morton, and it’s directly related to the changes he’s made to his repertoire. Morton has decided to lean on a two-seam fastball more heavily than just about anyone in baseball, and as Dave Allen has noted, the two-seam fastball and the slider have the largest platoon splits of any pitches in baseball. Two-seamers are great against same-handed batters, but aren’t an effective weapon against opposite-handed hitters.
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