The Hangover: Luis Perdomo Is Getting Better

While searching deep in the bowels of the internet on Sunday night for a Trevor Cahill article, I found some interesting nuggets on Luis Perdomo.

(Note: Most of these numbers don’t include last night’s start.)

Interesting nugget No. 1: Perdomo has gotten a 71 percent groundball/BIP on his sinker, ninth in the league among pitchers with at least 50 sinkers thrown.

This probably isn’t a huge surprise given Perdomo’s well-documented groundball ways, but it’s a six percentage point improvement over last season, and it’s led to a league-leading 68 percent groundball rate overall this year. Part of Perdomo’s success involves him keeping the ball on the ground, and his home run rate is significantly improved over last season.

Interesting nugget No. 2: Perdomo has a 53.7 percent whiffs/swing rate on his curveball*, second-best in all of baseball.

*Brooks Baseball identities Perdomo’s breaking pitch as a curveball, although it’s often referred to as a slider. We’ll call it a curve for now. 

Hmm, well, this is an interesting development. Perdomo’s whiffs/swing rate on his breaking ball last year was just 37.2 percent, 39th in the league. That’s still not a bad number, but the big jump forward has made it lethal this year. Plus, he’s getting batters to swing at it 46.5 percent of the time in 2017. Mike Pelfrey (yes, that one), who leads the league with a 66.7 percent whiffs/swing rate on the pitch, has coaxed just 9 swings on 53 curves. Unlike Pelfrey, Perdomo is succeeding both in getting batters to swing at his breaking ball and then getting them to miss it.

Here are a couple of swinging strikes from last night—where Perdomo got eight whiffs on 13 swings on the curve—for your viewing pleasure:

Interesting nugget No. 3: Perdomo is throwing his curveball 29 percent of the time this season, a nine percentage points jump from last year.

Okay, this isn’t that interesting, but it follows a trend we’ve identified this year, with some Padres pitchers simply throwing more breaking balls. It makes sense, too. If you have a good breaking pitch or two, a pitch that’s getting swings and misses, why not throw it more often?

Combine the last two nuggets and all the sudden Perdomo is a strikeout pitcher. He k’ed nine Brewers last night in six innings (without Eric Thames and a few others, that was a relatively weak lineup, for what it’s worth), with no walks, bumping his K/9 up 8.91 this year. Last year Perdomo got just two seven-plus strikeout games in 20 starts; this year he has that many in his last two outings.

Perdomo looked like a dude with a power sinker a year ago, someone who’d hopefully succeed by inducing a bunch of worm-burners. This year he’s still getting those ground balls, but he’s also getting strikeouts. That’s just a good pitcher, someone who could hold down a place in this rotation for a while. His DRA has dropped from 5.43 last year to 3.79 so far this season, his cFIP from 102 to 86.

There are concerns still, of course. As mentioned on the broadcast last night, getting through a lineup a third time has been a challenge for Perdomo. Further, the lack of a changeup has left Perdomo susceptible to lefties, as they’ve OPSed .890 off him as a group so far in his career. The development of a more well-rounded repertoire might help Perdomo in both of the above trouble areas. In fact, Eno Sarris wrote about as much back in spring training, tagging Perdomo as a pitcher in need of a new pitch.

But let’s not get ahead of ourselves. Perdomo’s barely 24, still just a couple years removed from the Florida State League. He’s already shown the ability to make rapid adjustments at the big-league level just to get to this point. Let’s see what he can do now.

(Note No. 2: Josh Shepardson wrote about some of these stats (and more) the other day at FanGraphs. h/t: Friar_Faithful.)

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