Predicting the 2019 Arizona Diamondbacks rotation

The Opening Day rotation for the D-backs appears largely set. Zack Greinke will get the ball there, and will be followed by Robbie Ray, Zack Godley, Luke Weaver and Merrill Kelly (in some order, though that’s the most likely one, I’d say). So rather than ask you whether or not our starting pitcher candidates would be on the roster next month, we asked you to rank them in order of the number of innings they would pitch for the 2019 Diamondbacks. Unsurprisingly, this list was not all that different from the order produced in the ranking phase of this exercise. But it wasn’t identical. Here’s the list by expected innings pitched: the number in brackets is where the player came when ranked by quality.

1. 1.2 - Zack Greinke (1.2)
2. 2.5 - Robbie Ray (2.2)
3. 3.2 - Zack Godley (3.7)
4. 4.6 - Luke Weaver (4.8)
5. 5.3 - Merrill Kelly (5.8)
6. 6.9 - Matt Koch (8.2)
7. 7.9 - Taijuan Walker (6.3)
8. 8.4 - Jon Duplantier (7.7)
9. 8.6 - Taylor Clarke (9.0)
10. 10.4 - Ryan Atkinson (10.7)
11. 10.5 - Taylor Widener (9.5)
12. 10.5 - Rickie Nolasco (11.1)
13. 12.1 - Troy Scribner (12.3)
14. 12.7 - Joel Payamps (12.6)

If you want an overall view, if the number for a player is higher than the number in brackets, they’re expected to get more work than their “quality” would suggest. A lower number means they’ll see less than they deserve. The main change was probably expected: Koch moving up from ninth to sixth, leap-frogging both Walker and Duplantier by expected workload. This is likely a result of Koch having two ways to get work in: both as a starter and as a possible long-man in the bullpen. Most of the other candidates are really “starter-only” names. On the other hand, Widener dropping into an effective tie with Nolasco, and below Atkinson, comes as something of a surprise.

Interesting to note that Ray is the only one of the front five starters who is expected to pitch less than his “quality” figure. This is something Jack mentioned in the comments, but it is worth looking at his workload by innings pitched, since he came over to the D-backs [all figures below include both major- and minor-league appearances]

• 2015: 169.1 IP
• 2016: 174.1 IP
• 2017: 166.2 IP
• 2018: 130.1 IP

That’s an average of 160 innings, and since becoming a full-time starter in 2016, an average of 28 major-league starts. That’s not bad. But it ranks Robbie only tied for 37th among starting pitchers over the last three seasons. With the departure of Patrick Corbin (=18th by the same metric) from Arizona, Ray will need to step up and become the everyday starter the team needs this year. The other interesting unanswered question is, who’ll get bumped from the rotation to make room for Taijuan Walker, when he comes back, potentially around late July? However, the words of Robert Burns, “The best laid schemes o’ mice an’ men / Gang aft agley,” apply heavily to rotations. We can cross that bridge when we come to it!