Could the 2024 rotation be the best rotation in Arizona Diamondbacks’ franchise history?

The Arizona Diamondbacks just made an Opening Day buzzer beater addition, signing veteran left-hander Jordan Montgomery to a one-year deal on Tuesday evening. Montgomery is a massive boost to an already strong rotation that will house Cy Young finalist Zac Gallen, fellow veteran lefty Eduardo Rodriguez, as well as stalwart Merrill Kelly, and youngster Brandon Pfaadt. With the addition of Monty, one has to wonder if this could be the best rotation in the Diamondbacks’ history.

Let’s first look at arguably the best rotation in Diamondbacks history; their 2002 team. This team ended up having the best FIP, WHIP, second best ERA, lowest opponent batting average against, as well as the most innings pitched and fWAR among any year of Diamondbacks’ starting rotation. They were led by two Cy Young frontrunners: Randy Johnson and Curt Schilling. Miguel Batista, Rick Helling, and Brian Anderson also rounded out the Diamondbacks’ starting rotation that year.

Four of the D-Backs’ five starting pitchers had an ERA+ of 100 or greater. But both Schilling and especially Johnson were far out in front of everyone else. Schilling clocked in with a 140 ERA+, while Johnson had a 195 ERA+. None of the other Diamondbacks’ starters had an ERA+ above 106.

Last year, Merrill Kelly had +3.9 bWAR, while Gallen clocked in at +5.4. Kelly had a 132 ERA+, while Gallen sat at 125. Pfaadt struggled to find his footing in the first half of the 2023 season but had a respectable 4.14 ERA and 3.89 FIP in August and September. Plus, he was lights out in the D-Backs’ NL Pennant run with 22 IP, eight earned runs allowed, 26 K’s, and only five walks. He also had a sub-4.00 xFIP and SIERA in the final two months of the season. Although Eduardo Rodriguez will miss the first two weeks of the 2024 season, he had a 3.30 ERA, 3.66 FIP, 134 ERA+, and +3.4 bWAR.

Montgomery is coming off a career year in 2023 where he had a 3.20 ERA and 138 ERA+, both of which were the best marks of his career. His 3.56 FIP was another career low, and was the first time he pitched over 180 innings with 188.2 frames with the St. Louis Cardinals and Texas Rangers. Montgomery had +4.1 bWAR last year.

In my opinion, the Diamondbacks’ current rotation is a lot more well-rounded. They don’t have a Randy Johnson-caliber starter right now, someone who has a whole head, shoulders, and torso above the rest of the rotation. But I think that all of Gallen, Rodriguez, Kelly, Montgomery, and Pfaadt could finish the season with an ERA+ between 120 and 135, a 15% window of one another. The dropoff from the ‘02 Diamondbacks’ best ERA+ to second best ERA+ was 55%. I don’t think the difference between even the D-Backs’ best starter and worst starter is going to be that wide this year.

I think the Diamondbacks’ 2024 rotation will end up better than their 2002 rotation, but they’ll get there in a much different way. The 2002 rotation had one Hall of Famer, and another pitcher who would have been in Cooperstown had it not been for his off-field antics, but their 3-5 starters were about league-average arms. Meanwhile, the 2024 rotation might not have two all-time great talents but five quality starters, each of whom could give this team an ERA of 3.50 or lower.