Peter Strzelecki and the Brewers' Brilliance on High Fastballs

According to Statcast, the Brewers allowed a .243 expected weighted on-base average (xwOBA) on fastballs in the upper third of the zone last season. That was tied with the Dodgers for the best mark in the league. However, the Dodgers threw such pitches almost 2,200 times, while the Brewers threw just 1,800 of them. Only the Rangers and Yankees attacked the top of the zone with heat less often. 

That was with Josh Hader in the mix for over half the season, too. Whereas high fastballs made up just 7.4 percent of all the Brewers’ pitches, Hader used them 14.1 percent of the time. As you would imagine, he was also one of the best pitchers in the league when he did locate there, with a .190 xwOBA allowed. Now that he’s gone, can the Crew come anywhere near having the same success at the top of the zone?

The answer to that question depends heavily on Peter Strzelecki, as does so much of the team’s bullpen hope this year. The former undrafted free agent is such a fierce and awesome competitor, with such a compelling story, that it can be easy to miss the technical and new-age aspects of his brilliance. They’re there, though. Strzelecki can dominate at the top of the zone, thanks to the way his fastball movement interacts with his funky delivery.

Peter Strzelecki is an example of a pitcher who has an elite 4SFB without flashing triple digits. His flat VAA of -4.2 deg induces a SwStrk% of 14.5% and Whiff Rate of 29.9% which are both well above league average (10.4% and 21.5%). pic.twitter.com/Us2Vth4Tcc

— Matt Hinkley (@MH_CSP_Pitching) October 27, 2022

The “flat VAA” referenced in that tweet is a flat Vertical Approach Angle, one of the favored new toys for pitching gurus. It’s a measurement of how steep the trajectory of a pitch is when it enters the hitting zone. For fastballs (and especially high fastballs), a flatter VAA is almost always a good thing, because hitters have trouble seeing and matching that movement. Thus, they swing under the ball, whiffing or popping it up, or they freeze and let a called strike go by.

A fastball’s VAA is mostly a function of its velocity, its spin axis, and the heights at which it leaves the pitcher’s hand and enters the strike zone. Strzelecki, who used high fastballs even more often (16 percent of all pitches) than Hader did in 2022, is just one of several remaining Brewers who have a flat VAA. Freddy Peralta is another. Anyone with that combination of a riding fastball coming out of a low release point will tend to have this characteristic.

When it comes to high heat, though, the challenge is as much a mental as a physical or a geometric one. A pitcher has to attack the top of the zone with conviction, and they need a certain level of fearlessness. Like Hader and Peralta, Strzelecki has that. He’s unabashedly and unreservedly eager for the fight. 

“I always say, you can’t spell ‘compete’ without ‘Pete’,” he said in a podcast interview last year, and while almost no one in MLB could say that without it being rendered hokey through self-awareness, he pulls it off. It’s not some awesome insight, though in plenty of ways, Strzelecki is a thoughtful guy. It’s not a mantra that will miss bats for him; his pitches have to do that. With his mentality and the unique traits of his fastball, though, Strzelecki can deliver much of the swagger and the dominance at the top of the zone that Hader did. The Brewers should continue to win in that area, thanks in large part to their new setup man.