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Towards a 2024 Diamondbacks roster: Pitching depth

It’s not just about the fifth starter.

MLB: Arizona Diamondbacks at Toronto Blue Jays Nick Turchiaro-USA TODAY Sports

The front of the Diamondbacks’ rotation looks quite solid at this point. There’ll be Zac Gallen and Merrill Kelly at the front, with Eduardo Rodriguez and Brandon Pfaadt behind them. The fifth spot in the rotation is likely to be decided in spring training, with Tommy Henry and Ryne Nelson probably the leading candidates. Though there’s still time for another free-agent to be signed, and of course, things can change dramatically - not least due to health - over the almost three months between now and Opening Day. It does look better than last year’s Opening Day rotation, with Arizona basically replacing Madison Bumgarner and Zach Davies with Rodriguez and Pfaadt.

However, that’s just the tip of the iceberg, because five starting pitchers won’t be enough. Last year, the D-backs used no less than fourteen different starters. [Bonus point: how many can you name? Answer at the bottom] Now, you may be thinking, that’s a result of the team using openers: I mean, Joe Mantiply started almost as many games as Bumgarner. But the team also used fourteen in 2022, and a startling sixteen in 2021. It’s typically not just a case of needing to rotate somebody into the fifth spot either. To get some idea of what the team needs, I looked at data for the past ten full seasons (so 2013-2023, excluding 2020), and found the number of starting pitchers and the games started by the top four combined.

D-backs starting pitchers

Year Pitchers #1-4 starts
Year Pitchers #1-4 starts
2013 9 112
2014 11 100
2015 12 109
2016 10 108
2017 10 120
2018 11 122
2019 12 103
2021 16 89
2022 14 121
2023 14 109

For those who prefer a visual depiction, have a chart.

You can see that the number of starters has been creeping up in recent seasons, though the games by the front four in the rotation has been fairly static, sitting in the 100-120 range most seasons. This increased number of starters isn’t particular an Arizona thing. 2013 was the last time the D-backs used fewer than ten starters in a season: they were one of eight teams to do so that year. Last year, there were only three such teams. In 2022, it was just two. At the other end, in 2023 the Athletics used no fewer than 24 different starters over the season, and the Royals 23, both more than any other team in baseball history. But they still got 91 and 99 games respectively out of their most-used quartet.

To be conservative, we’ll just use the ten-year average for the D-backs which works out at a dozen starters (11.9, to be precise). The front four - we’ll assume for now they’re going to be Gallen, Kelly, Rodriguez and Pfaadt - average 109 games a year. So we have to look for eight starting pitchers behind them, who will cover the remaining 53 games. I’m going to try and limit it to actual starting pitchers, rather than listing openers. I’m sure Torey Lovullo would prefer to go that route. His hand was kinda forced into it, especially in the post-season. I’m pretty sure the words “World Series Starter Joe Mantiply” were not on the plan as drawn up by him and Mike Hazen.

40-man roster

The first place we can look beyond the obvious quarter is on the existing 40-man roster. That’s where we find Tommy Henry and Ryne Nelson. Immediately, rhere’s one name there worth consideration, but has to be crossed off. Drey Jameson certainly would be a contender, but damaged his UCL in July. After trying to rehab it, he eventually underwent Tommy John surgery in September. That’s him effectively off the board until 2025. But also present are Slade Cecconi and Bryce Jarvis, who both were occasional (Cecconi 4, Jarvis 1) starters for the team in 2023. Right now, they figure to slot in behind the candidates for the fifth starter’s job.

There are some other possibilities. You might have forgotten entirely about Corbin Martin, and that’s understandable. His season ended before it had even begun, suffering a torn tendon in his right shoulder during spring training, which also required surgery. Last we heard, Martin had got out to throwing from 105 feet; proving he’s healthy will be the first thing before he is even considered. This has been a long-term problem for Corbin, who has only once reached a hundred innings in a season - and that was back in 2018. Blake Walston is the last prospect, added the 40-man this winter. Still only 22, he held his own in Reno, with a 4.66 ERA, though his K:BB (104:93) could definitely use much improvement.

Non-roster invitees

We’re still some way off having a full list of those who have signed minor-league contracts with an invitation to spring training, or the prospects who will be there. If we look at the non-roster invitees from last spring, you’ll find Cecconi, Jarvis, Pfaadt and Walston present, so who knows. Maybe someone from this year’s batch will find themselves starting a World Series game come October? Even discounting that, the 2023 NRIs were good for a total of 23 regular-season starts, so I’d definitely not be surprised to see them contribute in some way this season. Though if last year is any guide, it’s more likely to be prospects rising to the top, than the grizzled veterans.

We’ll have our usual NRI round-up nearer spring, but a couple of names stand out. Left-hander Logan Allen signed a couple of days ago, but is not to be confused with the Cleveland pitcher of the same name. This one was a top 100 prospect before 2019, but has struggled since then. He has at least been pitching, which is better than Chris Rodriguez. He was claimed off waivers by the D-backs from the Angels in October, then removed off the 40-man roster. Drafted out of high-school back in 2016, Rodriguez’s total pro workload is still barely past 130 IP, with a total of 3.2 innings since August 2021. I definitely expect more names to be added over the next few weeks, so stay tuned.

On the prospect front, of those who will might start off in Reno this season, Jamison Hill and Luke Albright are names to know. Both were part of the Amarillo Sod Poodles rotation for 2023, each making 25 starts. Hill had the better ERA, posting a 4.35 in another league and park which is very hitter-friendly (team ERA: 5.37). But Albright’s K:BB ratio was better, striking out 136 over 112 innings. Below Reno, perhaps we’ll see someone surge from Double-A to the majors, like Andrew Saalfrank did this year. Yu-Min Lin, still only twenty, is someone tipped to go places - but it would likely be a stretch if those places included Chase Field in 2024.

Depth chart

Here’s the 12 pitchers I would pick, right now, as the ones from whom the Diamondbacks can draw in the 2024 season. Again, I want to stress how early this is, and an awful lot could change. But I’d not be surprised if as many as two-thirds of those listed could start for Arizona at least once over the coming campaign.

  1. Zac Gallen
  2. Merrill Kelly
  3. Eduardo Rodriguez
  4. Brandon Pfaadt
  5. Ryne Nelson
  6. Tommy Henry
  7. Slade Cecconi
  8. Blake Walston
  9. Bryce Jarvis
  10. Logan Allen
  11. Luke Albright
  12. Jamison Hill

In alphabetical order, the fourteen starters used by the D-backs in 2023 were: Madison Bumgarner, Slade Cecconi, Zach Davies, Zac Gallen, Tommy Henry, Drey Jameson, Bryce Jarvis, Merrill Kelly, Joe Mantiply, Scott McGough, Ryne Nelson, Kyle Nelson, Brandon Pfaadt and José Ruiz.