Logan Gilbert Enters the Spin Zone

Logan Gilbert is having a good, but relatively pedestrian year compared to his previous seasons. His expected bases allowed per plate appearance (xEB/PA) has increased to 0.431, which puts him closer to league-average, compared to his low of 0.397 (remember lower is better for pitchers' xEB/PA) in the 2024 season.

Gilbert's expected bases allowed per plate appearance by season. Lower is better, and 2026 is his weakest mark since 2022.

However, his four-seam fastball became a different pitch on June 16 against the Orioles at T-Mobile Park. Before then, he threw 429 four-seamers across 14 outings. They averaged 2,115 rpm (6th percentile). Since June 16, he has thrown 313 of them across six starts at 2,305 rpm (league-average).

Four-seam spin rate each time out. The jump on June 16 is a step, not a gradual climb.

Velocity has increased too, from 95.5 to 96.7, though it didn't move until a start after the spin did.

Four-seam velocity each time out. It steps up on June 21, one start after the spin jumped.

And hitters, who had been missing 16.7% of their swings against the pitch, started missing 24.0% of them. Arm-side run is higher too, 5.2 inches before against 7.3 since, though that one has been climbing all season rather than jumping in June.

A mid-season jump like that is usually something dull, and the pitch-level data is detailed enough to go looking. It records where Gilbert releases each ball, how far down the mound he gets, and what axis the ball is spinning on. Almost all of it says the same thing: nothing changed.

It isn't how far out front he gets. His extension has been between 7.37 and 7.74 feet all season with no trend. He is letting go of the ball at the same distance from the plate.

It isn't a new spin direction (the axis reads 207.3 degrees before June 16 and 207.7 after). That doesn't rule out a new grip, though, since the axis tells us which way the ball is spinning, not how the seams are turned against it.

It isn't his arm slot. He releases the ball 5.85 feet off the ground since June 16 vs. 5.87 before.

An interesting one to mention is Gilbert's release point, which has drifted steadily toward the third base side all season, from 0.51 feet off the centerline in March to 1.22 feet in July. That is 8.5 inches, and every pitch he throws moved with it, with no change in height or extension. So the whole delivery has shifted sideways, either from a different spot on the rubber (which is only 24 inches wide) or from a different stride. Either way it is slow, and most of it was finished before June 16, so it does not arrive with the spin.

Release point each time out. The side drifts steadily toward third base across the season while the height never moves.

Finger pressure or seam orientation could be behind the extra spin, but none of that shows up in the tracking data, so we would be guessing. What we do know is that the four-seamer has been working for Gilbert and he knows it, because he has been throwing it more .. a lot more!

Pitch mix each time out. The four-seam takes over after June 16 while the cutter nearly disappears.

The results have followed. His modeled xEB/PA for the season peaked at 0.476 in mid June and has come down to 0.431 by late July.

Season-to-date expected bases allowed per plate appearance, peaking in mid June before coming down through July.

Data: MLB Stats API