Fastball Freddy’s Fast New Windup

There are two things that jump out to me about Freddy Peralta’s start to the 2021 season. The first is that the man once known as Fastball Freddy is throwing said fastball at a career-low rate. The second is that he’s added some new moves into his windup that may be increasing his deception. Amidst all that change are some underlying command issues that suggest he still has things to work on.

Let’s start with his windup, which I’ve become absolutely fixated on. It’s not at all the windup I remembered him having, and I’m mesmerized by it.

Like an alarm clock going from a restful existence into a blaring beep that jiggles itself off the nightstand, Peralta has added some chaos to his delivery. What once was a fairly normal over-the-head windup and cross-body release has gotten more complicated. The leg kicks up higher, his feet are more caffeinated, and he starts in a more hunched position as if to make his over-the-head motion easier to attain. His new windup is nearly a half a second faster from start to release. And did I mention his feet? His feet!


If I were watching those two windups without context, I would assume the 2021 version was from early in his career and the 2019 version was one constructed over years of refinement. If changes are to be made, it’s usually in the name of getting rid of wasted movement and fine-tuning things for increased repeatability. Peralta has seemingly done the opposite.

What I’m wondering is whether the frenzy in his windup is causing issues. Though Peralta has a 51 ERA-, a 79 FIP-, and a massive 42.5% strikeout rate, he doesn’t quite have the ironclad peripherals that rotation-mates Corbin Burnes (who’s on another planet right now) and Brandon Woodruff boast, as he has the second-highest walk rate in baseball and the worst first-pitch strike percentage. Peralta has never had the best command — going into the year, Eno Sarris’ Command+ metric had him 6% worse than league average — but things seem to be going in the wrong direction.

Showing Freddy Peralta's F-Strike% dropping over the course of his career.

League average F-Strike% is 59.5%; Peralta’s 45.2% is nowhere near it, and you can see above that this problem has been getting worse. His Zone% is also poor: His 38.9% rate is fourth worst in baseball.

You’d think that a fastball-heavy pitcher like Peralta would want to pound the strike zone (or at least be able to). It’s not like fastballs are a great chase pitch, and it’s not like he is a great chase pitcher, with an O-Swing% that is fifth lowest in the majors. If you dive into his pitch mix, though, you get a better idea of how he’s been thriving despite such poor control.

Freddy Peralta’s Pitch Mix
Year FB% SL% CB% CH%
2018 77.6 19.5 2.8
2019 78.4 20.5 1.1
2020 65.8 24.1 10.1
2021 55.9 35.5 3.7 4.9

In case you’re new to Peralta, that’s why he’s called Fastball Freddy; he throws it a lot. His 76.1% fastball usage from 2018 to ’20 would’ve been tops on the leaderboard if he had enough innings to qualify.

This year looks quite different. The slider that he debuted last year is taking on a bigger role, and it’s getting better results this year as well. By pitch value, it’s been the fifth-best slider in baseball, and it carries a stern .160 wOBA. The sample size is small, and the two best outings for his slider both came against the same team, so its usage and success could be a result of the matchup. In his most recent start against the Pirates, for example, he only threw the slider 26.4% of the time. It remains to be seen where that number will ultimately settle.

His slider also has less drop this year than last. Check out the difference in movement:

Slider Movement
Year xMov zMov
2020 8.6 -1.7
2021 8.6 -0.2

And here are a few new sliders to look at.

That is a flat slider — even flatter than Julio Urías’ new slider that Ben Clemens wrote about this week. That flatness is causing hitters either to miss it completely or to stay under it. Peralta is getting above-average whiffs on his slider, which is propping up his overall SwStr% — eighth best in baseball at 16%.

Now let’s take a look at Peralta’s pitch type data, with league average numbers for context.

Pitch Type Data
Exit Velocity League Avg. Launch Angle League Avg. Infield Flyball% League Avg. GB% League Avg. SwStr% League Avg.
Fastball 89.4 90.5 37 18 36.4 8.8 20 33.9 12.7 11.2
Slider 81 86.9 19 13 20 8.1 27.3 43.6 22.6 16.6

Both of Peralta’s pitches are doing similar things: getting whiffs, getting soft contact, and getting elevated contact. Unsurprisingly, he’s got the fifth lowest ground-ball rate in baseball. Flyball pitchers walk a fine line between success and disaster. Just look at two of the pitchers who have given up fewer grounders than he has: Madison Bumgarner and Jacob deGrom. So far it’s been much more deGrom than Bumgarner for Peralta, as his grounder-less repertoire has induced extremely soft contact and a ton of popups. In fact, he has the exact same HR/FB% and infield fly ball rate — a comical 27.8% — as deGrom does this year, and pop-ups are a beautiful thing for a pitcher who gets himself into trouble with walks.

But it wouldn’t be a piece about Fastball Freddy unless it included his fastball.

If you are intrigued by what Peralta’s fastball is doing, I encourage you to read Justin Choi’s recent article on Vertical Approach Angle. Much of it applies to Peralta, as his (relatively) short stature (5-foot-11) and extension (7-foot-1) give him the flattest fastball in the game, which is the exact thing that gets hitters to hit pop-ups. Thankfully, he isn’t afraid of catching them.

Peralta’s flatter slider looks like a legitimate weapon, and paired with his well-established fastball, it could be the key to him taking the next step. He’ll need to sharpen up his command to make that happen, though, and whether he can do that while keeping the chaotic new windup remains to be seen.





Luke Hooper is a designer and writer at FanGraphs. He lives in Portland, Oregon, longing for a major league team to materialize.

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