2024 Diamondbacks Camp Battles: 5th Starter

Two former top prospects will battle it out for the final spot in the Opening Day rotation.

The most intriguing camp battle for the Diamondbacks this spring will be the final rotation spot. The two leading candidates are no strangers to this particular situation, as they were in a similar battle a year ago. 

Arizona will be entering Spring Training with four of their five rotation spots already accounted for between Zac Gallen, Merrill Kelly, Eduardo Rodriguez, and Brandon Pfaadt. Gallen, Kelly, and Rodriguez all have a track record that speaks for itself, while Pfaadt's impressive postseason performance earned him the No. 4 role.

During the Eduardo Rodriguez introductory press conference, general manager Mike Hazen answered a question about a competition for the final rotation spot. Hazen named left-hander Tommy Henry and right-hander Ryne Nelson as candidates and also their previous track record will be the main determining factor.

LHP Tommy Henry

2023 Stats: 17 G, 16 GS, 89 IP, 4.15 ERA/4.30 xERA, 16.8% SO, 9.2% BB; 2024 Projection

Based off Hazen's comments, Henry enters the competition with the inside track to win the competition. His game is based off establishing early count strikes with his fastball, then going to his slider and curveball to induce chases for either strikeouts or weak contact. Henry ranked above average amongst major league pitchers in chases (78th percentile), hard-hit rate (87th), and barrels (60th), suggest a potential soft contact inducing skill could be developing. Despite only getting 16 starts, he ranked third on the team in Quality Starts with six.

The case for Henry is simply being the less volatile option of the two leading candidates along with a better 2023 performance. Despite having inferior raw stuff compared to his competitior, he has a better feel for his overall arsenal of pitches and could potentially have a legitimate run prevention skill if he's able to further induce chases and weak contact in 2024. The key will be continued refinement of his changeup, which would allow him to be able to attack both sides of the plate vs. right-handed hitters more effectively. Once he has that pitch, he should settle into a No. 4 role for the foreseeable future.

The case against Henry is mainly one of upside, which hardly will factor in the decision. Henry's fastball is 91 MPH and without the weak contact profile doesn't have much going for him. However that's less of a concern, as he has the strongest track record of any of the non-established starting pitcher candidates.

RHP Ryne Nelson

2023 Stats: 29 G, 27 GS, 144 IP, 5.31 ERA/5.27 xERA, 15.5% SO, 7.4% BB; 2024 Projection

Nelson won the fifth starter role a year ago, but was unable to seize that opportunity. He lost the feel for his plus slider for much of the 2023 season, which in turn exposed his mid-90s fastball. He made 27 starts, moreso due to the overall health of the starting rotation than his actual performance meriting those opportunities. As a result, he enters the season on the outside looking in for the competition although it's possible he may make the team as a long reliever instead.

To make the Opening Day rotation, a spot would have to open up for Nelson. The only scenario that doesn't involve an injury would be if Henry had a bad enough spring that he couldn't be trusted with a rotation spot. Considering how much the 2023 track record will factor into the decision, that might not even matter. Looking at his arsenal, Nelson has a solid mid-90s fastball with a vertical shape and averages nearly 18 inches of induced vertical break, and a swing-and-miss slider when he's able to command it.

The case against Nelson is simply his 2023 track record was very poor. The D-backs need to see if he has a more consistent feel for both his slider and changeup to trust he'll be able to stick in the rotation other than a few spot starts or bulk relief. At the same time there's not much he can learn in Triple-A Reno, which is why it makes more sense for the team to carry a long reliever and let Nelson develop confidence against major league hitters.

Likely Winner

Henry is the overwhelming favorite to win this competition based off the two pitchers' respective 2023 track records. Carrying Henry would also give the D-backs a second left-hander in their rotation, allowing them to break up their right-handed starters. This is also a battle where the respective "loser" might not get sent down to the minor leagues, but instead the bullpen as a long reliever.