Top 40 Pitching Prospects (With Stuff+ Data!)
Analysis of the top 40 arms in the minor leagues accompanied by Stuff+ on EVERY arm
If you’re receiving this post in your email inbox, I encourage you to go to my substack site to read. The functionality of the tables will be much friendlier.
Below you’ll find my ranking of the top 40 pitching prospects in the minor leagues. The value-add of this list compared to the many other fantastic lists out there is that I have access to minor league pitch shape data for all levels. I’ve enlisted the help of Thomas Nestico to help me build a Stuff+ model to better understand the major league quality of these minor league pitches.
Random Notes…
My process for this exercise started by looking at Stuff+ before watching outings. In the future, I’d like to reverse this process and start with more tape-watching before looking at data. But it’s hard to not look at data when you get a big output of Stuff+ for the first time. So yes, this is a data-biased list.
I’m not ranking any pitcher who has already thrown in MLB. If you want to know where a pitcher would rank, just ask, and I can ballpark it. My reason for this is that I wanted to write up more pitchers who don’t have advanced data currently public.
This class of starting pitching prospects is relatively weak. The emergence of Grayson Rodriguez, Tanner Bibee, Brandon Pfaadt, Bryce Miller, and others have depleted this particular set of ranks. The names at the top of this list are also coming off lighter workloads from 2023 than previous years’ top prospects.
Stuff Notes…
For individual pitch types, Stuff+ shows that pitch’s value relative to other pitches of that pitch type. A 124 Stuff+ slider is 2 standard deviations (plus-plus) above the average MLB slider. This would equate to a pitch that’s around the 98th percentile in MLB—a rare offering to find in the minors.
Total Stuff+ distills the value of an entire repertoire into one number based on the usage of that pitch and the value each specific pitch type has towards run prevention. Therefore, a 100 Stuff+ curveball has a different level of contribution to run prevention than a 100 Stuff+ fastball.
A pitcher with a total Stuff+ of 112 would have an arsenal 1 standard deviation above the MLB average at preventing runs or an 85th-percentile MLB mix.
This scaling is slightly different compared to Eno Sarris’s model on FanGraphs, which also has a standard deviation of 12 for total Stuff+, but on an individual pitch level, has different standard deviations and averages. As a result, this Stuff+ may feel slightly deflated. That’s normal. These aren’t major league pitchers (yet).
I anticipate pitchers will see Stuff+ changes from the numbers below when they debut in MLB. This is a byproduct of development and also the inevitable data error some MiLB parks might possess. I hope that the amount of data for each arm below helps diminish any error.
The baseballs used below Triple-A are different than those used in MLB. This can create complications in projecting pitch quality. A general thing I’ve seen is that pitchers experience shape changes as they ascend, specifically from AA to AAA, generally in a manner that hurts their Stuff+. This varies arm by arm and even park to park.