Who Does Zach Davies Replace in Diamondbacks Rotation?

One of Brandon Pfaadt, Tommy Henry, or Ryne Nelson will likely cede their rotation spot very soon, at least temporarily

Zach Davies had a successful rehab start with the Amarillo Sod Poodles on this past Saturday, going 4 2/3 innings and throwing 69 pitches. He allowed three hits, walked one and struck out seven. The Double-A hitters in the Frisco Rough Riders lineup were no match for Davies' A-grade change up, which he had that night.  He had been rehabbing in the Arizona Complex League games, and this was his first affiliated team rehab start. 

Davies injured his oblique muscle just two games into the season and has not pitched in a major league game since April 8th. As of this writing it's not yet known if Davies will make another rehab start or be activated off the injured list for the weekend series at Chase Field against the Boston Red Sox that begins on Friday, May 26th. If he's not activated for Friday's start, and makes one more rehab start, then he would be back no later than May 31st.  Either way, a decision must be made by the Diamondbacks soon. 

Davies was brought back on a one year deal to provide innings and depth at the back of the rotation so the team could avoid having to use more than one rookie at a time in the rotation. His injury, coupled with the team needing to DFA Madison Bumgarner after just four terrible starts, resulted in the D-backs using rookie starters Ryne Nelson, Drey Jameson, Tommy Henry*, and Brandon Pfaadt for a total 21 starts out of 47 games already. (*Henry technically exhausted his rookie status in 2022 and is considered a second year player). The results for the group in total have been what one would expect, rough and inconsistent but with some bright spots. 

Jack Sommers

There have been just four quality starts in these 21 games, two each by Nelson and Henry. The cumulative record is just 2-5, but thanks to some hefty run support in their starts the team has survived with an 11-10 record.  It's put additional strain on the bullpen however, as the average innings pitched per start is just 4.8, compared to MLB average 5.2. 

Brandon Pfaadt would seem the most likely to be sent back to Reno to make way for Davies. He was the last man up, and has the worst numbers of the group. He also lines up exactly with Davies, as his next start would be the 26th against Boston. Pfaadt has pitched much better in his last two outings however. After allowing six homers in his first two outings, he's given up just one long ball in his 10+ innings of work, and just four earned runs. He would be a tough send out for the team.

Ryne Nelson is probably the least likely to be optioned. His Fielding Independent metrics, (FIP and xFIP) are more than half a run lower than his ERA, and he pitched well in his most recent start. The team has attached great importance to pecking order, and Nelson was the one who won the spring training "competition" which was always his to lose to begin with.  He hasn't pitched poorly enough to lose that position on the depth chart, and more importantly nobody else has pitched well enough to displace him. 

Henry has had some success inducing soft contact and keeping his pitch count low so he can get deeper into games, resulting in two quality starts. His 3.47 Pitches per plate appearance is by far the lowest of any starting pitcher on the team. The next lowest is Zac Gallen at 3.81, and the league average is 3.90.  Henry's strikeout to walk ratio of 13 K, 12 BB in 27 innings will need to improve if he's to have continued success however. The fact that he's the only left-hander in the rotation and is getting a little deeper in games to protect the bullpen will likely weigh heavily in the team's decision making.

Drey Jameson was optioned to Reno a while back of course, and it does not appear there is room for his return any time soon. It's encouraging that he's pitched well in his last couple of outings.  (12 IP,  3 ER, 2.25 ERA, 3 BB, 12K) If he continues to do that and one of the other starters falters he will get another chance. 

Illustrating just how difficult a choice this may be, a recent twitter poll on the topic returned some very split results and interesting conversation. 

I’m going to post this poll again on Wednesday. Pfaadt good outing yesterday. Henry and Nelson start on Monday and Tuesday

Who WILL (not should) Zach Davies replace in rotation when he comes back. He and Pfaadt both line up next Friday vs Boston

Thursday is off day

— Jack Sommers (@shoewizard59) May 21, 2023

The team is in Philadelphia for a three game set against the Phillies, starting this afternoon. Henry pitches the first game and Nelson the second. How they do in these outings could also impact what the team does next.  If they pitch well and the Diamondbacks decide to give Davies one more rehab turn, therefore giving Pfaadt the start against the Red Sox on Friday, then the decision is pushed out a week and gives the team more time to evaluate.  But Davies looked ready in his Amarillo start.  The only reason to not bring him back now would be pitch count concerns, but he should be good for at least 80-85 pitches at this point.  

Keep your eyes on Inside the Diamondbacks, for further news and analysis on this and all topics related to the team.