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Diamondbacks Game Preview #137: 9/9 @ Rockies

As Tommy Henry departs the rotation, we ask whether the Reno effect applies to pitchers too?

Arizona Diamondbacks v San Diego Padres Photo by Denis Poroy/Getty Images

Today's Lineups

Josh Rojas - 3B Ryan McMahon - 3B
Ketel Marte - 2B Yonathan Daza - LF
Jake McCarthy - DH C.J. Cron - 1B
Christian Walker - 1B Charlie Blackmon - DH
Daulton Varsho - RF Brendan Rodgers - 2B
Corbin Carroll - LF Randal Grichuk - CF
Carson Kelly - C Michael Toglia - RF
Alek Thomas - CF Elias Diaz - C
Geraldo Perdomo - SS Alan Trejo - SS
Zach Davies - RHP German Marquez - RHP

Roster moves

The Arizona Diamondbacks made the following roster moves:

  • Recalled RHP Taylor Widener from Triple-A Reno.
  • Optioned LHP Tommy Henry to Reno following Wednesday’s game.

And so, Tommy Henry returns whence he came, having posted a 5.50 ERA across seven starts in the majors, despite a glowing 3.83 ERA in 20 appearances. It got me to thinking about the impact of Reno. We all know and have seen that prospects almost never live up to their Triple-A stats. The hitter-friendly environment of the Pacific Coast League, powered by things like Reno’s almost Denver-like altitude of 4,500 feet, ensures that in the long term, we can typically expect a drop of 250-300 points of OPS when a hitter moves from there to the majors. You would expect this to help pitchers, even if the quality of opposition becomes higher. Is that the case?

I took a look at the pitchers who have thrown at least 15 innings for both the D-backs and the Aces during 2022. Here are the qualifiers, along with their IP and ERAs, first in AAA and then in the majors.

  • Tommy Henry: 108.0 IP, 3.83 ERA - 36.0 IP, 5.50 ERA
  • Corbin Martin: 77.0 IP, 6.08 ERA - 22.1 IP, 4.84 ERA
  • Tyler Gilbert: 44.0 IP, 7.57 ERA - 34.1 IP, 5.24 ERA
  • Edwin Uceta: 38.2 IP, 4.89 ERA - 17.0 IP, 5.82 ERA
  • Kevin Ginkel: 30.2 IP, 1.17 ERA - 17.2 IP, 4.58 ERA
  • Sean Poppen: 20.1 IP, 5.31 ERA - 25.1 IP, 3.91 ERA
  • J.B. Wendelken: 17.1 IP, 3.63 ERA - 29.0 IP, 5.20 ERA

If we add up all of the above lines, we get a total of 336 innings in Reno, with an ERA of 4.79. The same pitchers at the major league level have thrown 181.2 innings, with an ERA of 5.05. Rather than any improvement, we are still seeing an overall increase in their ERA when moving from AAA up to MLB. It is only about a quarter of a run higher, and that feels less than I would have expected: certainly less than the impact on hitters. I’d need to check a broader sample of pitchers making the transition, from outside the PCL. It may be that the relatively pitcher-friendly environment helps “soften the landing” for the promoted pitcher. But it does appear we can’t expect Reno ERAs to drop in the big leagues.