Inspiration.
The following question inspired me. It was from the Snake Pit Roundtable.
“One thing that isn’t is Ketel Marte and Geraldo Perdomo. What do they need to change to get the bats woken up?” — Blake Stokes
After looking at Geraldo Perdomo’s batting strengths, I wrote, “Geraldo Perdomo is doing nearly everything excellently. Perhaps if he could improve his launch angle sweet spot percentage, that would allow him to sustain his breakout from last season.” — Makakilo
Then, I discovered the Squared-Up Explorer
in the FanGraphs Lab (it also looks at Launch angles).
Let’s use the Explorer to look at squared-up and launch angles for Marte and Perdomo (games through 17 April).
The Approach.
For each pitch type, the metric to measure performance will be run value per 100 pitches found in Baseball Savant.
This season for Marte and Perdomo, the question to address (for each pitch type) is when fly ball squared-up percentage improved (for all pitches, and for batted balls near the ideal launch angle) did their performance improve? Likewise, when they worsened, did performance worsen?
Ketel Marte
The following table looks at his squared-up percentages for each type of pitch (both all pitches and for those at ideal launch angles). Also, it looks at the run value per 100 pitches as the performance metric.
Two observations follow:
- Marte improved last season’s results for sinkers, curves, and cutters. For each of those pitch types, he improved his squared-up percentages.
- Marte’s results against 4-seam fastballs is comparable to last season.
Marte does not appear to be in a slump for two reasons:
- His 0.45 RBIs per game compares well to last season.
- His improved squared-up percentages for five types of pitches.
Geraldo Perdomo
The following table looks at his squared-up percentages for each type of pitch (both all pitches and for those at ideal launch angles). Also, it looks at the run value per 100 pitches as the performance metric.
Four observations follow:
- This season, Perdomo is hitting four-seam fastballs better (higher run value per 100 pitches) than last season. It makes sense that his squared-up percentages are better than last season.
- Although his squared-up percentages are better for changeups, his run value dropped slightly (although it’s still positive). I’m expecting his batting results against changeups will improve this season.
- For curves, it did not seem to make sense until I saw that only 17% of his batted balls were fly balls.
- Perdomo’s table generally confirms that, for each type of pitch, squared-up percentages impact performance as measured in run value per 100 pitches.
Confirming that Perdomo is in a slump is his 0.2 RBIs per game, which is less than half of last season’s rate. Improving his squared-up percentages could help him break out of his slump.
Other Perspectives.
After considering the perspective that squared-up percentage is the key to improvement this season, you may want to compare it other perspectives.
Mike Hazen said Perdomo is working through his swing mechanics.
“He’s having a great approach [at the plate]. It seems like he’s gone through hitting the ball on the ground a lot to popping the ball up a little bit. I’m sure he’s working through some mechanical stuff.” — Mike Hazen, April 2026
Ben Seigel’s AZ Snake Pit article explains possible reasons for Perdomo batting:
- Fall in bat speed reduced results from balls-in-play.
- More swings at first pitches reduced the number of pitches per PA that Perdomo sees.
- Less swings at meatball pitches (perhaps pitchers are being more careful).
In a comment to Ben’s article, Preston Salisbury wrote that Perdomo’s .150 BABIP will not last [it will improve]. In games through 19 April, his season BABIP improved to .242.
Confirming the fall in Perdomo’s bat speed was this FanGraphs article (written after Ben’s article).
Summary.
Comparing performance to last season, changes in squared-up percentages seemed to have an impact on run value per 100 pitches.
Marte improved last season’s results for sinkers, curves, and cutters. For each of those pitch types, he improved his squared- up percentages. Despite the inspiring round table question, he does not appear to be in a slump.
Perdomo is hitting 4-seam fastballs better than last season. Nevertheless, his batting appears to be in a slump. Improving his squared-up percentages could help him break out of his slump.
