What the numbers say about Zack Wheeler’s start

Through four starts, the back of the baseball card numbers look like Zack Wheeler’s numbers. His 2.55 ERA, 2.70 FIP and .193 batting average allowed all rank among the best numbers he’s ever put up.

But he’s getting there in a much different way than he has in the past.

Coming off his thoracic outlet syndrome surgery last year, Wheeler has yet to recover his typical fastball velocity thus far, averaging 94.7 mph on that pitch. That’s down from 96.1 mph a season ago, and about 1 mph lower than the upper 95s he featured from 2022-24.

Perhaps not coincidentally, he’s seen a drop in his strikeout rate too, which sits at 23.2%, well below last year’s 33.3%. He’s simply not able to throw the ball by hitters in the zone right now.

The good news is, he’s not trying to.

Instead, Wheeler has exchanged strikeouts for groundouts, and at a pretty incredible clip. He’s generated a ground ball rate of 48.5%, his highest since 2021. Last year, his ground ball rate was 39.9%. It is one of the reasons he has been so efficient with his pitches this season.

Instead, Wheeler is turning more to his secondary pitches, throwing his fastball 34% of the time in his first four outings, down from 41% in each of the previous two seasons. With six pitches at his disposal, he’s been able to mix things up and keep hitters off balance (numbers from Baseball Savant).

• Fastball: 34%
• Sinker: 19%
• Sweeper: 14%
• Splitter: 13%
• Cutter: 10%
• Curveball: 9%

Without his usual velocity, Wheeler has amped up some of the movement on his pitches, too, specifically, the horizontal movement on his sinker and sweeper.

The top line is his sinker, which has slowly increased in horizontal movement since 2023. His sweeper, a pitch he first started using in ‘23, has seen a dramatic increase in it’s horizontal movement. Both pitches are generating 18 inches of horizontal run.

Folks, that’s a lot.

Those pitches are sweeping through and out of the zone in a way that has allowed Wheeler to remain in the 90th percentile in chase rate in MLB.

So while his fastball velocity, whiff rate and strikeout rate are all middle-of-the-pack right now, there are other areas in which Wheeler is excelling.

Is this a profile that will allow Wheeler to have this kind of success all season? His xERA of 3.51 and xFIP of 3.37 indicate there will likely be some regression. But even if Wheeler’s actual ERA ends up being around 3.50, it should still be seen as a solid contribution for a team that doesn’t require him to be the Cy Young candidate he was even a season ago.

Just be ready for the occasional blowup game where Wheeler’s movement isn’t as crisp or hitters start laying off some of those sinkers/sweepers on days when he doesn’t have his best command. Unless his velocity increases as the weather gets warmer, he’s going to have to be a bit more careful in the zone with his fastball.

Perhaps this is the beginning of a re-invention of Zack Wheeler. Perhaps it’s a one year situation as he recovers from surgery.

Whatever it is, the results have been encouraging.