Diamondbacks to promote touted prospect Ryne Nelson

Diamondbacks pitching prospect Ryne Nelson will make his MLB debut on Monday, manager Torey Lovullo told The Arizona Republic’s Nick Piecoro and other reporters. Nelson isn’t on the team’s 40-man roster, so at least one corresponding move will need to be made to create space for the 24-year-old right-hander.

A second-round selection in the 2019 draft, Nelson received some top-100 attention prior to the season, with The Athletic’s Keith Law rating him 74th on his list of baseball’s best prospects and Baseball America rating Nelson 96th. Law felt that Nelson was “the safe bet who offers the strongest combination of current stuff and command” among Arizona’s top pitching prospects, which was enough for Law to rate Nelson slightly ahead of other notable D’Back hurlers Drey Jameson and Brandon Pfaadt.

Nelson will be the first of that pitching trio to make the majors, though Nelson has had a rocky time in his first exposure to Triple-A baseball.  He has a 5.43 ERA over 136 Triple-A innings this season, with a 21.6% strikeout rate and 7.6% walk rate. That walk rate is Nelson’s best over his three pro seasons while his strikeout rate is by far his lowest, and he has also allowed 25 homers. However, as Piecoro notes, these results are certainly influenced by the hitter-friendly conditions of Triple-A Reno and in the Pacific Coast League in general.

Nelson’s fastball is his signature pitch, averaging only around 93-94mph but with a lot of spin. BA gives Nelson’s fastball an impressive 70 grade on the 20-80 scale, while Pipeline is a little less bullish with a 60 grade. Pipeline’s scouting report also gives plus grades to Nelson’s curve and slider, and according to some D’Backs personnel, the slider could eventually become the right-hander’s best pitch.

It is worth noting that Nelson is still something of a work in progress as a pitcher, as he was a two-way player at Oregon and didn’t turn solely to pitching until 2019.  Between that relatively late start and the canceled 2020 minor league season, BA’s scouting report feels Nelson “could still have significant growth ahead of him.”  For example, he has made enough improvement with his control that he now looks like a viable starting candidate, whereas there was some feeling that Nelson would ultimately end up as a reliever.

The Diamondbacks will see what Nelson can do in Monday’s start against the Padres, and possibly for the rest of September. Lovullo said the club is moving to a six-man rotation in order to rest some arms and keep everyone fresh in the final month of play, with an eye towards juggling the rotation in advance of a September 20 doubleheader against the Dodgers. After an day off on September 8, the D’Backs play18 games in a 17-day span before their next off-day.