Underrated MLB Pitching Prospects At The Lower Levels According To RoboScout


Image credit: (Photo by Tom DiPace)

RoboScout is moving to the mound.

So far, we’ve used this series to look at underrated hitters across both the lower levels and upper levels of the minors. Today, we’re investigating pitchers at the lower levels who RoboScout feels are undervalued. This was a bit more difficult because most pitchers who do well in the lower levels are either quickly promoted or already highly rated. Still, there are some gems to be found among the arms down at the complex and at Low-A and High-A.

Understanding Pitch Metrics

We define various pitch types and explain terminology associated with ball-tracking devices that may be useful for this story.

Arizona and Florida Complex Leagues

David Matoma, RHP, Pirates

Matoma reportedly sat at 93 mph when the Pirates signed him at 16 years old out of Uganda. The righthander, who turned 17 in February, made his professional debut this year showing substantially increased velocity, sitting at an impressive 97 mph with over 20 inches of IVB and a -4.5 VAA. He also has an impressive slider for a teenager, sitting in the upper 80s with above-average spin. The pitch is already especially impressive considering his amateur development in Africa. Yes, we have fewer than 50 pitches logged for him. But pitch metrics stabilize quickly and, quite frankly, Matoma is showing an incredibly intriguing arm with the potential for two plus pitches and nearly no available track record for what his development path could be. He’s someone to watch as a potential high-leverage bullpen arm with extreme risk.

Sandy Mejia, RHP, Astros

Mejia was a 2022 international signing out of the Dominican Republic. At the time, he had a four-seam fastball that averaged 89 mph, a 79-mph slider and a changeup he mixed in 10% of the time. His stuff took a step forward in 2023 with the FCL Astros. Mejia’s heater gained 3 MPH and 200 more RPMS while throwing it with 19 inches of IVB and 10 inches of arm-side run. Because he throws from an over-the-top release height, it does not have the modern flat VAA that one would expect, but still generated above average whiffs and “plus” run value. Florida Complex hitters only saw four-seamers with that type of induced vertical break roughly 10% of the time. His slider, which he only threw 15% of the time, also gained 3 MPH from 2022 and got plus whiffs. Mejia also debuted a curveball which had high spin and extreme spike from his high release point, also generating plus whiffs and extremely poor contact quality against. Although he is definitely a development project, Houston has had great success developing pitching prospects with this kind of toolset — Cristian Javier and Jose Urquidy come to mind — whom did not get the minor league acclaim commensurate with their future major league success. RoboScout thinks Mejia might be another name to watch in that mold. He was the fourth-highest ranked pitcher in the Complex Leagues despite only a 100 Stuff+ per the RoboScout internal model due to the 38% strikeout rate, 0.86 WHIP and 2.17 ERA in 29 innings in the FCL as a teenager.


Here’s how the Astros scouted and developed pitchers like Cristian Javier and Framber Valdez.


David Sandlin, RHP, Royals

Perhaps this is a bit of a cheap selection considering we had the 2022 11th round selection as a helium name back in June when he was carving up hapless Low-A batters with his mid-90s fastball and plus slider. Unfortunately, an undisclosed injury cut his season short. Assuming he comes back for the 2024 season, RoboScout — who had him ranked ninth for the level on the season, despite him not being young for the level — will have its visual sensors squarely on him. Looking back through previous seasons, the closest season in production for a 22-year-old starting pitcher in Low-A was Corey Kluber in 2008 for the San Diego Padres affiliate. 

Here’s how closely they compare:


Although Sandlin’s WHIP is higher than Kluber’s, Sandlin’s ball percentage for his two primary pitches are both better than league average and not suggestive of pending control issues. He’s one to watch for 2024 assuming a full offseason recovery and readiness for opening day in 2024 — likely in High-A.

Jose Corniell, RHP, Rangers

Corniell ranked 10th in RoboScout’s Low-A rankings after finishing with a 25.3% K-BB%, 0.92 WHIP, and 2.70 ERA over 43.1 innings at 20 years old. Acquired from the Mariners in 2020 for Rafael Montero, the Dominican righthander won the South Atlantic League pitcher of the month for August and was named the Rangers Minor League Pitcher of the Year. His arsenal starts with an above average-to-plus slider per our Stuff+ model, which has 10 inches of horizontal sweep and gets 37% chases out of the zone. His curveball is nearly as perplexing to hitters. It comes in at over 2800 rpms and generates over a foot of horizontal run, leading to 50% whiffs. His fastball is solid at 94 mph and performs well up in the zone.

Logan Henderson, RHP, Brewers

Henderson was selected in the fourth round of the 2021 draft and underwent Tommy John surgery in March of 2022, ultimately throwing just 13.2 innings prior to this season. In 2023, however, Henderson’s fastball/change-up mix befuddled Low-A hitters to the tune of a 26.6% K-BB%, 0.97 WHIP, and 2.75 ERA in a relatively hitter-friendly Carolina ballpark. Although his four-seam fastball averaged only 92 mph, which is average for the level, it had nearly 20 inches of IVB and a flat -4.5 VAA. Both are one standard deviation higher than average and work well with his low release height. Henderson has an above-average zone% and better-than-average xwOBAcon, meaning he can throw the fastball for strikes and keep contact quality down. That results in a top-tier run value for the pitch. Changeup-heavy pitchers are generally successful against lower-level hitting, but Henderson’s changeup does have 10 mph of separate from his fastball and gets above-average whiffs and chases. He’s also still just 21 years old. Durability is the main question, but he’s RoboScout’s fourth-ranked pitcher in Low-A, suggesting a back-of-the-rotation outcome is a reasonably high-probability outcome.

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