Luis Perdomo is developing in the Majors

Luis Perdomo was one of the most exciting unpolished arms available in last December’s Rule 5 draft, and the San Diego Padres went out of their way to acquire him. He was one of four players that San Diego pulled out of that event, as the Rockies picked him from the Cardinals system and immediately traded him to San Diego. Perdomo had never pitched above the High-A level and was known to be a high-risk, high-upside profile.

In previewing the Rule 5 Draft, Baseball America’s J.J. Cooper said Perdomo “has pitches—a 93-95 mph fastball and a tight slider that darts downward—that flash plus to go with a clean delivery and average control.” Because Perdomo was such a raw pitcher, Cooper also expected that a move to the bullpen would allow Perdomo to focus on those two potential plus offerings.

Unfortunately, that did not work out early in the season, as Perdomo ran a 250 ERA- and 139 FIP- in 26.0 innings thru the end of May. He also didn’t stick strictly to two pitches. He threw his new split-finger fastball roughly 11 percent of the time and split the remainder of his fastballs pretty evenly between a sinker and a fourseam grip. None of his pitches performed particularly well, but his fourseam fastball was specifically crushed by opposing hitters.

By the end of May, the Padres had already found themselves in fifth place and 11.5 games back in the division. At this point, despite the lack of success in a less demanding role, the team decided to convert Perdomo back to the starting rotation — potentially to more traditionally develop this high-upside prospect in a season that already seemed out of hand. Interestingly, his conversion to the rotation also coincided with the change in repertoire that was expected before the season (note that, due to its vertical movement, his slider is classified as a curveball).

Over the last two months, Perdomo has lessened his use of the splitter and all but scrapped the fourseam fastball. He’s now throwing sinkers and sliders roughly 93 percent of the time. Normally, moving a pitcher to the rotation while limiting his repertoire would lead to an increase in his degree of difficulty as a pitcher, but weirdly, Perdomo has performed significantly better since the change.

Since becoming a starter, Perdomo has seen his strikeout rate increase (14.8 percent to 17.2 percent), his walk rate drop by nearly half (12.0 percent to 6.3 percent), and his groundball rate jump to an elite level (50.0 percent to 61.7 percent). His season line has improved to the point that he has a 91 DRA-, an above-average total performance mark.

What’s the secret? His sinker is thrown just as hard as the fourseam fastball, but it features far more life than the other grip, and batters have had a harder time squaring up the pitch. Very significantly, his fastball command appears to be improving as well, and his strike rate has climbed since the transition.

Perdomo has spent the last three months developing better command of his sinker, which is already a hard-thrown pitch with good movement. Additionally, throwing the slider for fewer strikes isn’t the end of the world. Padres manager Andy Green mentioned in June that Perdomo is “...a live arm that misses right now over the middle of the plate, and as he gets more experience he’s going to miss corners a lot more and that will be better.” He’d probably prefer to be throwing the slider for some more strikes, but he is at least missing out of the zone as opposed to missing over the plate.

Using a slider with a lot of hard, vertical break (again, PITCHf/x classifies the pitch as a curveball) offers the added potential of a limited platoon split. The splitter has been thrown for more strikes in its limited use since his conversion, but even if it doesn’t come around, improved command of the above two pitches gives Perdomo impact Major League potential.

There’s definitely a lot of work left to do, but Luis Perdomo still features impact raw stuff, and and his command is coming along. Once it became apparent that the Padres weren’t contending, the big league club took the opportunity to manage Perdomo with a focus on development, to make up for the time he’s missing in the Minor Leagues this season. Not only has he regained some of his prospect sheen, the Padres have seen improved results in 2016 as well.

While other “stashed” Rule 5 picks such as Tyler Goeddel or Joey Rickard will likely need significant Minor League seasoning in 2017, Perdomo’s development at the highest level means he will more quickly be a factor in the Padres’ Major League plans.

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Spencer Bingol is a Contributing Editor at Beyond the Box Score. He can also be read at Crashburn Alley. You can follow him on Twitter at @SpencerBingol.