Milwaukee Brewers: Wily Peralta Tinkering with Curveball

The Milwaukee Brewers big righty starter has struggled against left-handed hitters in his career, and it looks like he’s fighting back.

Wily Peralta hasn’t been a great starting pitcher for the Milwaukee Brewers. Heck, sometimes he’s downright frustrating. He throws hard, but doesn’t strike out batters. He pitches to contact, but suffers from high walk rates.

Now it looks like Peralta is addressing one of his biggest weaknesses; his performance against left-handed hitters. Wily has been solid against right-handed batters in his career, to the tune of a .705 opponent OPS. Not earth-shattering, but solid.

Lefties, however, have slashed .291/.350/.465 against the flamethrower. This is largely due to his lack of a consistent out-pitch against those hitters. He has a change-up, but it’s not a great pitch and he uses it sparingly.

Recently, however, websites that record Major League pitches have begun identifying an increasing number of Peralta’s pitches as curveballs.

And while the software for identifying pitches isn’t perfect, it’s the first time in years these sites have seen consistent curves from Wily.

According to Brooks Baseball, Peralta threw just seven pitches between 2012 and 2016 (including Spring Training) that qualified as curveballs. That accounted for 0.07% of the pitches he threw over that period.

It’s not clear why he threw those pitches, since they were so rare. Perhaps they were meant to be sliders or he really did throw about one curve per year over that time.

Since the start of 2017, Brooks Baseball has logged 28 curveballs from Peralta. That’s 8.16% of his pitches, spanning Spring Training and his first two starts this year.

Eight percent is no accident: Wily Peralta is tinkering with a new pitch. Further evidence is easy to come by. Half of those curveballs (14) have been thrown in the 2017 regular season, with the other half obviously coming in spring.

Of those 14 regular season pitches, 13 have come against left-handed batters. That’s 16.25% of his pitches against lefties this year. Against lefties, he’s thrown the curve more often than the changeup (8.75%) and the same amount as his slider. Peralta is clearly trying to figure out how to better defeat his lefty opponents.

If one source isn’t enough proof, consider FanGraphs’ pitch recognition program (recording only regular season pitches), which prior to this year had logged just four curves in Peralta’s career (all in 2011). It has logged 12 Peralta curveballs this season.

Back to Brooks Baseball and their 28 curves. The average velocity of those pitches is 79.56 MPH. The average velocity of the 95 sliders he threw in that same time period was 84.86 MPH. That’s more than five miles per hour of separation. It’s definitely a different pitch.

Why haven’t we seen at least a few articles discussing this revelation, like we did with Jimmy Nelson when he did virtually the same thing in 2015? A couple of reasons:

First, Wily Peralta has thrown just 14 in the regular season, according to Brooks. That’s a hair under seven percent of the time. Nelson, by contrast, threw his curve 21% of the time in 2015.

Also, Peralta’s curve has a serious lack of depth, and looks a lot like his slider. According to this handy article from FanGraphs, the average curveball has a value of pfx VMov of -5.8. That’s to say that the average curve breaks 5.8 inches downward compared to a pitch thrown exactly the same way but with zero spin.

That hypothetical pfx VMov of 0.0 from a spinless pitch, then, is our baseline. Back to the average curveball, -5.8. Jimmy Nelson’s career curveball pfx VMov according to Brooks is -5.67, which is to say that it breaks just a little less than a league average curve.

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Of course, I’m crossing between Brooks’ and FanGraphs’ numbers, so this comparison won’t be perfect, but it should be close.

Wily Peralta’s 28 pitches have a pfx VMov of just -0.40. It’s important to remember, 0.0 doesn’t mean zero drop. Peralta’s pitch still drops.

Consider that the average four-seam fastball has a pfx VMov of 8.9. So these curveballs are dropping  a lot more than the average fastball, but they’ve got very little depth compared to other pitchers’ curves.

Peralta’s curveball drops just two inches farther than his average 2017 slider, which has a pfx VMov of 2.15. Again using Jimmy Nelson’s career numbers as an example, the vertical drop for his curve and slider are -5.67 and 0.47, respectively.

Nelson’s offerings are two clearly different pitches. Anyone familiar with baseball will quickly identify the difference between his spike curve and his slider. For Peralta, though, that difference has been minimal.

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So the pitch is very much a work in progress, but it’s a promising sign that Peralta is still fighting to improve against lefties. Even if his curveball never becomes a particularly good one, any additional, usable pitch, helps keep an opposing hitter guessing.