Diamondbacks pitching prospect Ryne Nelson has re-discovered his old fastball velocity

Coming into the season, I had Ryne Nelson as the top pitching prospect and #5 overall with a solid shot of developing into a middle of the rotation arm. Nelson was coming off a season in which he produced a 3.51 ERA, which is downright elite in the crazy run scoring environments he had to pitch in with Amarillo, backed up with outstanding peripherals. Nelson punched out nearly a third of the batters he faced with Amarillo with a solid walk rate of just above 8%. While his corresponding FIP was 4.06, the high home run total can be explained away by the homer-happy environment in Amarillo with an elevation of 3600 feet, relatively dry climate, and winds that can turn the park into a band box.

The scouting report on Nelson from Fangraphs listed Nelson’s velocity as 93-96 MPH with a top velo of 98, earning a 60 present grade and a 70 future grade. Nelson fits the organizations mold of a pitcher with a vertically oriented movement profile on the 4-seamer coming out of a vertical arm slot, as they took him in the 2nd round of the 2019 Draft. Nelson was able to make the transition from reliever to starter as he delivered 116 innings in 22 starts between High A and AA last season, with no worse for the wear.

Heading into 2022, Nelson made a start for the Diamondbacks in a Spring Training game. I went to check his Statcast breakdown and saw a troubling trend. The velocity and the spin were both way down from expectations, with Nelson seeing a lot more low 90s and a spin rate that averaged just under 2000 RPM. For a pitcher as fastball-dominant as Nelson was in 2021, that right there was a red flag and cause for concern. Was this velocity drop a hidden injury or was it just simply a dead arm phase considering that Nelson had no reps in 2020 and had to ramp up in 2021?

So far in 2022, Nelson has made 12 starts with Reno with no hint of a single injury. Perhaps having the pandemic shortened season in 2020 then the ramp up in 2021 was the cause for the velocity drop. I’ve taken an average of Nelson’s average velocity and spin to see if there was any relation to his performances on the season.

When looking at this table, the main takeaway is a massive jump in velocity and spin rate starting with his 10th start of the year. In his first 9 starts, Nelson averaged 92.3 MPH on his 4-seamer and the spin rate averaging 1935 RPM. Only twice has his fastball averaged more than 93 and the same number of starts his fastball has a spin rate above 2000. In his last three, Nelson has averaged over 94 MPH and the spin rate well over 2100 RPM including a max velocity of 97.4 MPH. It’s also showing up in his bottom line results as over those three starts Nelson has accumulated this statline: 17 IP, 12 H, 7 R (6 ER), 6 BB, 24 K. That’s good for a 3.18 ERA, which is consistent with the 3.17 mark he posted between High A and AA last year.

With three starts with his 2021 fastball velocity back, we’re hoping it’s the end of a dead arm phase and Nelson can finally get the results he’s looking for in AAA. A sustained run with this velocity and results will give us a better idea of how major league ready Nelson is. Depending on how the second half of the season goes, Nelson could be in the D-backs rotation by September to get an evaluation at this level.