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  • How the Evolution of Freddy Peralta Made Him the New Ace of the Brewers

    Matthew Trueblood

    For a few years, now, the Brewers have had a Big Three in their starting rotation. There was always a fairly clear hierarchy among the trio, though. Now, that pecking order might need to be updated.

    Image courtesy of © Jeff Curry-USA TODAY Sports

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    If they don't change anything over the final week, the Brewers will have Corbin Burnes lined up to pitch Game 1 of the National League Wild Card Series a week from Tuesday, with Brandon Woodruff set to go in Game 2 and Freddy Peralta pitching either Game 3 of that series or (if the Brewers win the series in a sweep) Game 1 of the NLDS. That makes sense, given where these three have long stood in relation to one another. Burnes was the Cy Young Award winner two years ago, after being the breakout star in 2020. Woodruff has the most seniority of the group, is the oldest, and has been the most consistent over the half-decade during which they've been staples of this pitching staff.

    Peralta has always been considered the wild card of the bunch. He came up younger than they did, with a shallower arsenal of pitches and some occasional control issues. He struggled in 2019 and worked mostly in relief in 2020, before breaking out and earning shared billing with the other two in 2021. Fairly or not, he's never quite garnered the same respect or accolades as have Burnes and Woodruff.

    It's time for that to change, because Peralta is now the best of the bunch. He's quietly made himself as dominant and well-rounded as any starting pitcher in baseball, and if he stays hot, he could be the biggest X-factor in what the Brewers hope will be a deep run this October.

    By now, you've probably heard quite a bit about Peralta's new slider. In case you've missed it, though, let's talk a bit about it. Just before the All-Star break, Peralta tweaked the movement profile of his slider. It wasn't an extreme, drastic alteration, but it happened. That slider (one of two breaking balls for Peralta) used to be more of a sweeping slider, with greater lateral movement and less vertical depth. You can see the sweeper shape in the plot of his pitch movement prior to the change at the beginning of July.


    By contrast, note the tighter clustering and the different shape of the scatter since the start of July. Peralta's slider (the yellow dots) is now fractionally less distinct from his curveball (the blue ones), but it has a greater movement differential from his fastball (red), 


    The new version is a bit firmer, too, coming in perhaps a mile per hour harder than the old one. It's simply a pitch he commands better, and he can fool hitters better with it, too, for a couple of notable reasons.

    Firstly, Peralta is making it much harder than in the past for hitters to lock in on his release point and pick up the spin of the ball--because he's varying his release more than he ever has before. Here's a scatter plot of all his release points in 2022.


    Here's the same chart for 2023.


    Note the slight shift toward third base, but more importantly, notice the greater vertical spread in his release points. He's allowing himself to let his release creep slightly higher on the curveball, but disguising that from hitters by varying his release point more than in the past on all his other offerings, too.

    Typically, this would be bad news. Pitchers who have a lot of success talk about repeating their release point well. Pitchers who repeat their release point well have a lot of success. Really good, tight clustering of release points is one way to make it hard for hitters to find a cue that lets them guess which pitch is coming, and it's generally been accepted as the best way to both keep a hurler healthy and keep them throwing strikes.

    Another way to look at the same thing, though, is to consider release point distribution as a spectrum, where the thing you most want to avoid is being average. Either repeat your release perfectly, because of stellar mechanical efficiency, or scatter it enough to make hitters uncomfortable and force them to widen their focal point when they're trying to pick it up out of the hand. Just don't fall right in the middle. It seems an awful lot like Peralta has made the conscious choice to lean toward the latter means of putting hitters on the defensive.

    We can say that with some confidence, because Peralta has not only toyed with hitters utilizing this newfound dimension of deception, but shown excellent command, as well. Here's the average height (as it crosses the plate) of his pitches to left-handed batters, by month, for his entire career. Spot the point at which he figured something out with his four-seam fastball, and cleaved to it.

    Brooksbaseball-Chart (94).jpeg

    What we're seeing, in essence, is Freddy Peralta achieving satori--taking on properties and reaching levels that were beyond him before--through a series of small changes. At the root of them all, beginning a bit before the slider alteration and catalyzing the new approach of letting his release points diverge and attacking the top of the zone with his fastball, lies his newfound ability to use his entire arsenal.

    I first wrote about this in June, after a start against the Pirates in which Peralta made unusually heavy use of his changeup and both breaking balls. Ever since, in different ways, he's been doing the same thing. He's reshaped the slider and relocated the fastball, but it's the subtle twiddling of dials--a few more changeups here, an extra curve there--that has allowed him to level up recently. Against lefties, he just keeps gently pressing that changeup use upward, trying to find the place where it might start to have negative returns. He hasn't yet gotten there.

    Brooksbaseball-Chart (88).jpeg

    Against righties, though, he's doing much the same. It's just easier to miss it, because he remains primarily focused on the fastball and slider. The changeup has crept in especially invidiously. The hitter is looking up and away, for that fastball, and they're trying to stay back on the slider when it snaps down and away, but Peralta is increasingly getting to them with the change instead, down and in, like a back-foot breaking ball to an opposite-handed batter.

    Brooksbaseball-Chart (89).jpeg

    Peralta has figured out that his fastball works best in the area above the belt and away, and thus, he's tweaked the slider to move in a way that better suits the setup pitch: he can start them going toward the same place, without the hitter being able to say, "Slider; let it go," and have the ball skid off the plate for a ball.

    Peralta still has the capacity to ratchet up the sweep on the slider. He's done it a few times since (largely) switching to his tighter, more vertical pitch, when the scouting report has led him to work inside on righties more with the fastball. That's how he dominated the Marlins last time he saw them, earlier this month. Sunday will mark an interesting test of whether he needs to change his approach (radically or almost subliminally) when seeing an opponent twice in such close proximity. 

    In one sense, though, he passes that test already. Peralta violates one of the nearly inviolable laws of pitching: hitters hit him worse as his starts progress. The first time through the order this year, opponents have a .686 OPS against Peralta. The second time through, that number drops to .647. The third time, it's .573. That's extraordinary. Of the 159 pitchers who have faced at least 100 batters the first time through the order this year, Peralta ranks 57th in opponents' weighted on-base average (wOBA). Take the second, third, and fourth times through and lump them together, and of 151 qualifying starters, Peralta has allowed the seventh-lowest wOBA. The only pitchers with a higher strikeout rate than Peralta's 30.1 percent from the first flip of the lineup card onward are Atlanta ace Spencer Strider and Mets rookie sensation Kodai Senga.

    This isn't an entirely new skill for Peralta. In his career, he has allowed a roughly flat OPS based on times through the order, which is an achievement in itself. For most pitchers, that number steadily rises, as they tire and hitters get a better look at their stuff. Still, he's doing something different and better this year--and specifically, in the second half, as this new version of him has come fully into bloom. Of the 104 pitchers who have faced at least 125 batters the second, third, and fourth times through the lineup since the break, the lowest wOBA allowed belongs to Peralta--a staggeringly anemic .190. For a bit of context, hitters' wOBA against Devin Williams in 2023 is .215. Peralta is bettering that even as opponents see him a second and third time within a game.

    How did he turn this particular corner? Small changes in pitch usage can make a big difference, and in a pitch mix becoming as rich a symphony as Peralta's, there are plenty of small changes available.

    Here's how Peralta attacked lefties based on the pass through the order in the first half.

    Brooksbaseball-Chart (92).jpeg

    This is a pretty common pattern. Pitchers try to establish their fastball early, and go more to offspeed and breaking stuff as the game progresses. The theory underpinning that approach is radical only in its simplicity: A guy can't scope and shoot at a pitch they haven't yet seen. It's common sense, and (to some extent) it works. It's why pitchers with deeper repertoires can better resist the degradation in performance that comes each time through, but it's also one of the misunderstood drivers of that progressive penalty itself. Hitters know you'll show them the fastball first, then go with soft and spin more as the game wears on. They look for that.

    Here's what Peralta has done against lefties since the All-Star break.

    Brooksbaseball-Chart (93).jpeg

    That's a lot more changeups. It's also interesting, though, in the way it reflects Peralta's evolution beyond the first, simplest level of pitch sequencing theory. He (and catchers William Contreras and Victor Caratini, all in cooperation with the Brewers' pitching coaches) has seen past the principle of using fewer heaters as the game goes on. He's differentiating the changeup and using the curveball and slider more interchangeably, rather than the changeup and the curve. That change has been the real breakout star of his recent run. It's the pitch that makes everything else work better.

    Let's look at how Peralta has dealt with righties this season, in the first half:

    Brooksbaseball-Chart (91).jpeg

    and in the second: 

    Brooksbaseball-Chart (90).jpeg

    The first thing that jumps out is that, rather than that bowtie-shaped progression where he works fastball-heavy, then brings the secondary offering close to even, then goes back to the fastball the third time through is gone. Peralta steadily pushes the slider button more often as the game goes, having set hitters up better for it by making smarter, slightly greater early use of his curveball and changeup. By the third trip through the order, fewer than 45 percent of the pitches thrown by Fastball Freddy are heaters.

    Combine all these things--the ability to work deep into games without running into trouble, the skyrocketing strikeout rate on the back of his greater reliance on the slider and changeup, and the way he's maintained his control while moving his release point around a bit more--and you have one of the toughest hurlers in the game. Baseball Prospectus's value metric for pitchers centers on Deserved Run Average (DRA-). Peralta has the 12th-best among pitchers with at least 100 innings pitched this season, and he's 13th on BP's leaderboard for pitcher Wins Above Replacement Player (WARP). Both of those marks are better than those of either Burnes or Woodruff.

    In all likelihood, Peralta will start next weekend, during the final series of the season against the Cubs. Then, he'll be the team's third starter for the playoffs. In reality, though, he's their best starter at the moment, and he's the one whom Brewers fans should want taking the ball whenever the season is on the line the rest of the way.

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