In 2023, Mets left-hander David Peterson struck out 128 batters in 111 innings. Peterson’s strikeout price that 12 months, 26.0%, was twenty seventh within the league out of 127 pitchers who threw 100 or extra innings. He was tied with Zac Gallen, not far behind Luis Castillo, Gerrit Cole, and Zack Wheeler.
The subsequent 12 months, Peterson’s strikeout price dropped by greater than six factors, to 19.8%, however he shaved three-quarters of a run off his FIP, and greater than two runs off his ERA. This 12 months, Peterson is hanging out 21.5% of opponents, and after Wednesday evening’s complete-game shutout of the Nationals, his ERA is 2.49, which is 14th amongst certified starters.
However I believed hanging batters out was good! How did Peterson flip into this unhittable monster whereas working a decrease strikeout price than Shane Baz?
Nicely, the strikeout factor, it seems, by no means actually suited Peterson all that nicely. In 2023, he was working outdoors the strike zone, attempting to get batters to chase. He isn’t a tough thrower; his two fastballs largely work within the 91-93 mph vary. The 6-foot-6 Peterson does get a bit of bit of additional zip — or perceived zip, anyway — because of Ninety fifth-percentile extension, however he’s not gonna blow hitters away.
Nor was he getting hitters to chase; his O-Swing% in 2023 was 28.8%, bang-on league common.
In the meantime, when Peterson was working throughout the zone, hitters weren’t getting fooled both. Right here’s the warmth map from the 2023 for Peterson’s two fastballs (his four-seamer and sinker) to left-handed hitters:
Now, look. I don’t have all of the solutions, and that is only a idea, so take it for what it’s value. However I believe that throwing 91 mph fastballs down the center goes to result in a number of exhausting contact.
At the very least, that’s what occurred to Peterson in 2023. Lefties hit .264 towards his fastballs, with an xBA of .277. They had been much more relentless towards breaking pitches, towards which they hit .319. General, Peterson received tagged with an opponent wOBA of .357 (which is strictly Bryce Harper’s wOBA in 2025), and an xwOBACON of .416, which was within the backside 5% of the league.
A pitcher who permits that high quality of contact had higher miss a number of bats, and Peterson didn’t actually. His chase and whiff charges had been each good, however not nice, in 2023. The end result: an ERA over 5.00.
Nicely, dangling the baseball outdoors the strike zone didn’t work, so let’s attempt one thing totally different:
Zone Time for David Peterson
| Yr | Zone% | O-Swing% | Z-Swing% | Contact% | P/BF | P/Out |
|---|---|---|---|---|---|---|
| 2023 | 46.0% | 28.8% | 64.6% | 72.7% | 4.00 | 5.91 |
| 2024 | 49.4% | 29.4% | 66.0% | 77.0% | 3.68 | 5.17 |
| 2025 | 50.7% | 31.5% | 62.7% | 77.6% | 3.75 | 5.18 |
Beginning in 2024, Peterson started throwing the ball within the zone extra. His in-zone price has jumped about 4 factors for breaking balls, and an unbelievable 10 share factors for fastballs, from 2023 to 2025.
The obvious impact of this new method is that Peterson’s stroll price dropped from 10.2% in 2023 to 9.0% in 2024, and seven.6% this 12 months. Throw within the zone extra, challenge fewer walks. That is sensible. He’s additionally gotten extra environment friendly; every batter confronted is costing Peterson 1 / 4 of a pitch much less now than it did in 2023. Every out prices three-quarters of a pitch much less; two years in the past, 100 pitches received Peterson 17 outs. Now that many pitches get him 19.3 outs. That’s the distinction between 5 2/3 innings and 6 1/3 innings per begin.
What’s barely much less intuitive is that the place Peterson was getting lit up on contact in 2023, he’s dwelling with contact a lot better now. Opponents can nonetheless hit the ball exhausting — his hard-hit price is 46.3% this 12 months, which is fairly unhealthy out of context and truly up a pair ticks from 2023 — however they’re not doing as a lot injury.
Peterson has develop into superb at maintaining the ball off the barrel of the bat, and subsequently limiting the impression, so to talk, of exhausting contact. In his shutout victory over Washington, Peterson received simply 13 whiffs on 50 swings — a fairly pedestrian whole, particularly for a begin of that high quality. He additionally allowed 13 batted balls with an exit velo of 93 mph or extra — simply over half the 25 balls put in play towards him.
However solely a kind of 13 screamers got here off the bat at a launch angle between 15 and 50 levels. (That one, an eighth-inning double by Luis García Jr., was Washington’s solely extra-base hit of the day.)
Peterson doesn’t miss that many bats, and it’s not particularly tough to hit the ball exhausting towards him. However exhausting contact isn’t a lot good when it ends in a groundout or a medium-depth fly ball or, at most, a single. It’s exhausting to construct a giant inning by stringing collectively singles.
After I see a pitcher change his output to this extent, particularly when he pairs a decrease strikeout price with higher general numbers, I often count on to see a change in repertoire. A swap from a slider to a sweeper, a reworked changeup, or (tosses 1 / 4 within the swear jar) a brand new cutter.
Not Peterson. He’s nonetheless throwing the identical 5 pitches on the similar velocity, with about the identical spin charges and motion profiles.
What I’ll say is that Peterson is throwing his varied pitches, and particularly his two breaking balls, with a lot larger consistency.
Again when he was attempting to bait hitters to chase, Peterson splashed his slider principally anyplace mid-zone and beneath, and the motion was sort of everywhere. Right here’s how Peterson’s two breaking balls moved in 2023:
And right here they’re in 2025:
The slider particularly is rather more exact. So exact I instinctively need to name it sharper, although it’s not, actually. It doesn’t have exceptional motion in both route. However with extra constant motion, Peterson might be extra exact in the place he throws it. Right here’s the place the slider ended up in 2023:
And right here’s the place he’s throwing it this 12 months:
Whereas opponents tagged Peterson’s slider for a .355 wOBA in 2023, they’re solely wOBAing .225 this 12 months. A legal responsibility when thrown as a chase pitch, the slider is a significant asset now that Peterson’s throwing it for strikes.
See? You don’t must throw exhausting or rip off massive spin charges in spite of everything. You simply must throw strikes.