Chris Paddack Hasn’t Figured Out His Fastball Yet

After a phenomenal debut in 2019, Chris Paddack took a significant step back in his sophomore campaign. Much of those struggles could be linked to the performance of his four-seam fastball. In 2019, opposing batters hit just .204 against his four-seamer with a .275 wOBA. Those marks jumped to .308 and .413, respectively, in 2020. Likewise, Paddack went from a whiff rate on his heater of 23.2% his rookie year to 20.9% last season, a mark just barely over league average for a four-seamer. With that pitch and a plus changeup making up the majority of his pitch mix, the ineffectiveness of his fastball had a much larger impact on his results, as he simply didn’t have anything else in his repertoire.

This spring, Paddack decided to start looking at the analytics behind his fastball. In a mid-March media session, he spoke at length about what he learned about how its shape affects his results:

“Last year I was east to west. I was pulling off. My spin direction was outside of one, for y’all that know the baseball term of that. The axis of the baseball… I was getting two-seam run on my four-seam fastball.”

Here’s a look at the physical characteristics of Paddack’s fastball and its percentile ranks when compared within each pitch type:

When he was first called up, Paddack’s fastball featured elite vertical ride that made up for its average velocity and below-average spin rate. The spin he did impart onto the pitch was paired with a spin axis designed to generate tons of backspin. Last year, his overall spin rate fell a bit, but that’s not the real concern. Instead, the change in his spin axis had a drastic effect on the pitch’s shape. His heater lost over two inches of that elite ride and added some horizontal movement; it now moved like a two-seamer instead of a four-seamer.

Earlier this week, Kevin Goldstein wrote about why fastball shape is arguably more important than fastball velocity. As he put it:

“How do pitchers gain fastball effectiveness beyond what the radar gun says? By creating differentiation between their fastball and the norm by utilizing either rise or sink. The further one can get from the norm, the more effective the pitch can be beyond just the pure speed. Hitters expect a fastball to behave a certain way out of the hand and when it doesn’t, regardless of the direction in which it deviates, it creates challenges in terms of making hard contact, or any contact at all.”

Here’s what Paddack’s fastball shape looked like in 2019 with Goldstein’s “line of normality” added for effect.

And here’s what his fastball’s shape looked like in 2020.

This is what those two pitches looked like in motion:

2019:

2020:

His fastball still had a good amount of vertical ride to it, but it was much closer to what an average fastball looked like. With that additional horizontal movement, it became a lot harder for Paddack to locate his fastball on the inside corner to left-handed batters. If he missed his spot just a little bit, the new arm-side break would cause the pitch to leak out over the plate, which happened far too often. Left-handed batters posted a .290 wOBA against his heater in 2019; that mark jumped up to .409 last year. Right-handed batters performed far better against fastballs located on the outer half of the plate as well.

Paddack didn’t make any appearances in a Hawkeye-enabled stadium this spring, so his first start of the regular season on Sunday against the Diamondbacks was the first time we’ve been able to see analytics on his fastball. It wasn’t encouraging. He labored through four innings, walking as many batters as he struck out and allowing three runs on four hits, while his fastball looked nearly the same as it did in 2020. Here’s the same table from above with his 2021 data added in.

He was able to regain an inch of ride, but the amount of horizontal movement actually increased, and the spin axis was unchanged from last year. With more horizontal movement, Paddack’s fastball looks even more like a generic two-seam fastball that doesn’t sink, moving it closer to that looming “line of normality” that pitchers should be avoiding.

The other odd thing about Paddack’s start on Sunday was his pitch mix. For the first time in his short career, he made a start without throwing a single breaking ball. His curveball has never been more than an average offering, and he toyed with developing a cutter last year, but neither pitch made an appearance against Arizona; he simply relied on his fastball and changeup. Without either of those two breaking balls, Paddack is simply a two-pitch pitcher, and one of those pitches isn’t working the way it should be.

We’re just one start and 56 fastballs into Paddack’s season, so it’s possible he’s still digesting the analytics and is in the process of making adjustments to his fastball. But the early results aren’t encouraging. In that mid-March media session, he talked about how he would integrate data into his preparation process:

“These numbers aren’t just, you know, thrown on a computer or written down. They’re set in stone. Some guys use them, some guys don’t, but I think I’m leaning more on the side of: I’m going to run with those numbers and being able to break down those things during the season to see where I’m at.”

I’m sure the Padres analytics team has had plenty to discuss with Paddack as he prepares for his next start on Saturday.