Breaking Down the Arizona Diamondbacks' 2024 Starting Rotation Ahead of Opening Day

By adding Jordan Montgomery and Eduardo Rodriguez to Zac Gallen and Merrill Kelly, the Arizona Diamondbacks now boast one of the top pitching staffs in baseball.

The 2024 MLB regular season is about to begin, and that means it's time for every club to lock down its top five starting pitchers.

World Series champion Jordan Montgomery is the latest addition to the Arizona Diamondbacks' new-look starting rotation, as the club signed the veteran just 48 hours before Opening Day. Between Montgomery and Eduardo Rodriguez, the D-Backs made the most of free agency as they try to return to the Fall Classic, even if they won't be ready for the start of the season.

Here is a quick preview of how Arizona's starting pitching will look in 2024:

1. Zac Gallen, RHP
2023 Stats: 17-9, 3.47 ERA, 1.12 WHIP, 9.4 K/9, 5.2 WAR
2024 Projections: 12-10, 3.82 ERA, 1.22 WHIP, 9.3 K/9, 3.6 WAR

Although he only made his first All-Star appearance last season, Gallen has placed top 10 in NL Cy Young voting three times in four years. The 28-year-old is a true ace, and his career 3.21 ERA and 1.106 WHIP are further proof of that.

2. Merrill Kelly, RHP
2023 Stats: 12-8, 3.29 ERA, 1.19 WHIP, 9.5 K/9, 3.2 WAR
2024 Projections: 11-11, 4.17 ERA, 1.33 WHIP, 8.5 K/9, 2.5 WAR

Kelly has been a mainstay in the Diamondbacks' rotation ever since he came back over from Korea in 2019. Beyond the fact that he owns a 3.80 ERA in MLB action, Kelly is a reliable 35-year-old veteran who ranks No. 13 in all of baseball in starts over the last five seasons.

3. Tommy Henry, LHP
2023 Stats: 5-4, 4.15 ERA, 1.36 WHIP, 6.5 K/9, 0.7 WAR
2024 Projections: 3-3, 4.54 ERA, 1.40 WHIP, 7.4 K/9, 0.2 WAR

While Henry has been far from dominant in his 25 career MLB starts, he has at least been above replacement level. The 26-year-old also showed some decent signs of improvement in 2023, although it still remains to be seen if he can be a reliable member of the rotation for all of 2024.

4. Brandon Pfaadt, RHP
2023 Stats: 3-9, 5.72 ERA, 1.41 WHIP, 8.8 K/9, 0.3 WAR
2024 Projections: 9-9, 4.40 ERA, 1.26 WHIP, 8.2 K/9, 1.6 WAR

Pfaadt had a rollercoaster rookie season in 2023, putting up just three quality starts in 18 opportunities – plus the D-Backs lost all three of those games. From the NLDS through the World Series, on the other hand, Pfaadt owned a 2.33 ERA, .182 batting average against and 0.828 WHIP across four starts, showing why he was a top-50 prospect in baseball to begin with.

5. Ryne Nelson, RHP
2023 Stats: 8-8, 5.31 ERA, 1.42 WHIP, 6.0 K/9, 0.7 WAR
2024 Projections: 5-5, 4.74 ERA, 1.37 WHIP, 6.9 K/9, 0.3 WAR

After three promising starts in 2022, Nelson struggled in his first season of big league action in 2023. Still, the fact that he hung around for 27 starts is notable in its own right, meaning he can be relied upon to round things out when others are injured.

As previously mentioned, Montgomery will need some time to ramp things up after spending all of Spring Training in free agency. Rodriguez, on the other hand, is dealing with a strained lat and is set to open the season on the injured list.

Rodriguez is projected to go 9-8 with a 3.99 ERA, a 1.30 WHIP, 8.6 strikeouts per nine innings and a 2.2 WAR. Montgomery is projected to go 11-10 with a 3.96 ERA, a 1.27 WHIP, 8.1 strikeouts per nine innings and a 2.9 WAR.

When the two veterans coming over from the Texas Rangers and Detroit Tigers join the rotation, probably by mid-April, Henry and Nelson are the top candidates to get bumped out of the picture.

All 2024 projections are compiled using FanGraphs' Steamer model.

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