Did the Astros fix Rafael Montero before his season-ending injury in ’21?

Rafael Montero was unexpectedly acquired last year in the same trade the Astros got set up man Kendall Graveman from the Mariners, back on July 27. While Graveman is no longer a member of the team, Montero is still an Astro and is looking forward to being a part of Dusty Baker’s bullpen for the upcoming campaign.

But there’s a thing with Montero. Even though he was partially successful in 2019 and 2020 with Texas, he left horrible numbers behind in Seattle before joining Houston. Once he was traded, things suddenly started to go well for him. Despite pitching only four times for the ‘Stros, he made them count.

Before suffering a lat injury, he threw six innings of three hits and one unearned run while giving up two walks and striking out five hitters. Montero was good for a 0.83 WHIP and wasn’t as hittable as he was during his brief stint as a Mariner.

Moving forward to the 2022 season and assuming the Dominican righty will begin the season with the team, it’s fair to ask one question: Did the Astros fix Montero? Let’s try to answer that question based on his behavior on the mound last year.

To go straight to the point, Montero looked more uncomfortable to hitters as an Astro. Opponents registered a .304 batting average against him before the trade but fell to .158 over the cited four appearances with Houston. Besides that, his rivals went from making contact 79.3 percent of times to 70.7 percent, which could be a sign of progress.

As a Mariner, Montero was all around the strike zone, especially with his fast pitches. Take a look at the following image (heatmap of his total pitches):

Baseball Savant

Now, look at the one below (total pitches as an Astro). He was in total control and command of his pitches, consistently hitting a certain spot and staying down and away from right-handed hitters:

Baseball Savant

To that, you need to add the fact that Montero started to throw his four-seam fastball more often (from 34.5% to 46.0%) while diminishing his changeup usage (from 19.9% to 9.2%). Although I wonder why he almost stopped using a pitch that was good for him in the past, it was a good experiment for him and the Astros.

Take a look at this:

Fastball/Sinker outcome with the Mariners: 61.3% of total pitches, 39 hits, 117 at-bats, .333 BA, .258 xBA, .444 SLG, .367 xSLG, 85.2 EV

Fastball/Sinker outcome with the Astros: 65.5% of total pitches, 1 hit, 11 at-bats, .091 BA, .120 xBA, .091 SLG, .141 xSLG, 77.5 EV

For the Astros, it would have been interesting to see Montero during the rest of the season, but injuries happen. If Montero can repeat his success (from an admittedly very small sample) last year in 2022, he’ll be a pretty useful weapon for the Astros’ bullpen moving forward.