This was supposed to be the season that Jack Leiter took the next logical step with the Texas Rangers. Instead, it became kind of a disaster.

Leiter finished the season 3-7 with a 5.29 ERA. But he missed the final three months of the season after ankle surgery to remove an extraneous bone. He found out about the bone after first hurting the ankle in April. He tried to pitch through it but in doing so his mechanics became worse and he became less effective.

Leiter was never able to get himself in a position to return after he developed some biceps soreness in September. He pitched a live batting practice the final day of the regular season, but the Rangers fell short of making the playoffs and it didn't matter.

But what does matter is looking at Leiter’s deeper analytic numbers and trying to determine just how much his injury had an impact on his performance in 2026.

Breaking Down Jack Leiter’s 2026

There were only two things that were consistently good in Leiter’s MLB percentile rankings from 2025 to 2026. The first was his fastball velocity. In 2025 his fastball topped at 97 mph with which was in the 88th percentile. His extension off the mound was 6.9 feet, which was good for the 89th percentile.

In 2026 the fastball velocity topped 96.5 mph which was good enough for the 82nd percentile and his extension was at 6.7 feet, which was good for the 76th percentile.

The rest of his MLB percentiles were in the blue and relative static. As a sample:

Chase Rate: 25.1% (13th percentile in 2025); 30.4% (51st percentile in 2026);

Whiff Rate: 24.3% (43rd percentile in 2025); 25.4% (52nd percentile in 2026);

Strikeout Rate: 22.9% (53rd percentile in 2025); 23.4% (57th percentile in 2026);

Walk Rate: 10.4% (16th percentile in 2025); 9.9% (31st percentile in 2026).

Strangely, Leiter’s percentile ratings went up across the board. The percentile rankings are something he has no control over. If there is good news it’s that the chase rates, the whiff rates and the strikeout rates did nudge up a bit — just not into that red that you want.

But if there is any one thing that stood out it was his pitch usage and the pitch run value for each pitch. It shows just how much Leiter needs his fastball right now.

In 2025 he used the fastball 39% against left-handers and 39% against right-handers. Per Statcast he had a fastball run value of 12, which was in the 91st percentile. That pitch was a plus-9 against lefties and a plus-2 against righties. It also helped his other pitches, particularly against left-handed hitters. His slider, change-up and sinker were all plus pitches against left-handers in 2025.

That changed last season. He used the pitch 42% against lefties and 34% against righties. He didn’t experience a noticeable velocity drop, but his fastball was essentially a neutral pitch, and it dropped his fastball run value to a minus-2 and into the 32nd percentile.

It shows a couple of things. First, Leiter talked about needing to compensate for his delivery after he suffered the ankle injury. That surely played a role in the value of his stuff. Second, it shows just how reliant he is on the fastball to set up his off-speed offerings.

All his stuff took a precipitous drop in 2026 and when you see the difference between his fastball value over those two seasons, it's easy to see the cascading effect.

The good news is Leiter has proven that his stuff can be effective at the Major League level. The key to 2027 is avoiding injury, reclaiming his fastball’s effectiveness and turning one of his off-speed offerings into something that is less reliant on his fastball to set up.