The Astros have unleashed Rafael Montero’s fastball

Rafael Montero is off to an exceptional start in 2022, and it’s clear what the driving force behind his outstanding April has been:

In what may as well be an annual tradition, a recent addition to the Astros pitching staff is throwing more four-seam fastballs. Naturally, the results have been superb.

Montero has allowed just one run on the season across 9 ¹⁄₃ innings (0.96 ERA) while striking out 15 and walking a pair.

The stellar production is attributed solely to Montero’s four-seamer — all but one of his whiffs have come via the heater, which has averaged just a shade under 96 in terms of velocity. The fastball-centric approach has yielded a strikeout rate that is 98th percentile. It’s been one of the best pitches in baseball this year according to Baseball Savant’s Run Value metric.

When the Astros bolstered their bullpen at last year’s trade deadline, Kendall Graveman and Phil Maton were viewed as the headliners, and rightfully so — Graveman had an ERA of just 0.82 in 33 innings with the Mariners while Maton’s acquisition from the Indians came at a relatively high price in Myles Straw, the Astros’ starting center fielder.

Both played crucial roles in the club’s subsequent World Series run. Though Maton remains a member of the bullpen in 2022, Graveman’s departure in free agency during the winter created a considerable gap.

It seems Montero, the other, lesser-known player that Houston received from Seattle last July, has filled the void and then some, courtesy of his altered approach.

While the 31-year-old righty hasn’t experienced a marked increase in velocity, it appears the Astros have adjusted his location this year:

Montero had typically elevated his four-seamer in the past, but there does seem to be an emphasis on him locating it up and away, whereas in 2021 it was thrown inside more:

On the surface, location may be the only tangible change made to the pitch itself.

In terms of movement, Montero’s four-seamer has added a touch of extra vertical movement in 2022 compared to 2021, but overall there hasn’t been a substantial change in that department, nor in the spin rate one. The same can be said for his spin mirroring.

In addition to increasing the pitch’s usage and aiming it at a different quadrant of the strike zone, it’s possible the Astros are having Montero utilize the pitch in a way that’s unable to be discerned by publicly available data.

What is particularly interesting about Montero and his fastball purely from a data standpoint is that dating back to 2019, the physical properties of the pitch — such as its velocity, vertical and horizontal movement, vertical and horizontal release point, etc. — have compared similarly to Mets super-ace Jacob deGrom’s four-seamer, according to RotoGraphs’ Alex Chamberlain’s Similarity Scores.

Given that, it could be surmised that the Astros’ proprietary models provided similar findings, and that the plan all along was to have Montero heavily feature his four-seamer, something he had not previously done — its career usage rate before 2022 was 39.7 percent.

Were it not for last year’s season-ending lat strain that shelved Montero after he logged just six innings post-trade, there could be more to draw from. For the time being, it’s fairly clear that the Astros will stay the course with Montero and perhaps even double down further on his four-seamer.

Considering how elite the output has been, it wouldn’t be surprising if its current usage rate of 58.8 percent is closer to 70 percent a month from now.