The key thing to note is that the wild-card game is treated, for roster construction purposes, as a whole round of playoffs on its own. Teams taking part can therefore select 25 players with the sole intention of winning that single contest, then re-adjust the roster for the Division Series if they win. This basically gives them four additional spots for the game, to allocate as they see fit, because there is no need for more than a single starting pitcher.
Various things will be taken as read for the purposes of this exercise. In descending order of likelihood, these are
- The Diamondbacks will be in the wild-card game. Otherwise, what’s the point?
- It takes place at Chase Field. The team currently has a five-game lead over the second wild-card spot, and also owns the first tiebreaker against them. With 15 games left, the odds are definitely in our favor.
- We’ll play the Rockies. This isn’t certain: it could end up being a team from the NL Central instead - the Brewers have been gifted three additional home games, due to Hurrican Irma. But Colorado remain the most likely opponent, and I’m not sure it makes much difference, save perhaps informing the next choice.
Who should be the starting pitcher?
The wild-card is the ultimate “win or go home” contest: the only guaranteed sudden-death game on the major-league calendar (of course, there may end up being Game 7’s - or there may not). The entire point of MLB in creating the format, was that those teams have to send their ace to the mound for the play-in game, giving their opponent in the Division Series an advantage of missing the #1 starter. But it probably affects the Diamondbacks less than, say, a team like the Dodgers, who have an obvious ace, with a clear drop-off after Kershaw. In Robbie Ray and Zack Greinke, we have the best 1-2 punch in Arizona, since the heyday of Randy Johnson and Curt Schilling.
You can make an argument for Ray or Greinke as having been the “best” pitcher for Arizona so far this year. Ray has the better ERA, Greinke the better FIP. The table below sums up their statistics so far this season, and also breaks down how they have pitched in the likely environment and against the probable opponent. Obviously, those latter components have smaller sample sizes - significantly smalller for the latter in particular. But both those factors are ones which should be taken into account.
Ray vs. Greinke
While the overall numbers are similar, if we pick them apart a bit, we do see a clear difference. Greinke’s significantly better record at Chase, and also against the Rockies, suggest he would be the better selection for the wild-card game. If we win there, we would then have Ray starting the first game of the NL Division Series. I’m more than fine with this, because it would most likely be against the Dodgers. Over five starts against LA, Ray is 3-0 with a 2.27 ERA and has struck out over 41% of batters faced (53 of 129). Even if there wasn’t a wild-card game, we might well want to start off with Ray in Game 1 of the NLDS.
The starting lineup
It’s not clear who would catch Greinke. Jeff Mathis was Greinke’s personal battery-mate, until he took a foul tip off his hand and was placed on the DL August 22. It was reported recently that there is a chance Mathis could return by the end of the regular season. But I’m not sure I’d go with him in the wild-card game. Apart from the obvious offensive surplus, since Chris Iannetta has taken over, Greinke has, if anything, pitched better. Small sample size, but it’s a 2.02 ERA over the four starts with Iannetta catching. compared to 3.16 with Mathis. I’d not risk disrupting that, and so would start Iannetta.
Elsewhere, we should probably factor in the Rockies’ choice of starting pitcher. Their two best have been RHP Jon Gray and LHP Kyle Freeland, with ERA+ of 127 and 125 respectively. But according to a recent piece on Purple Row, RHP German Marquez is the choice - mind you, that was before the D-backs soundly beat him last night. Over the entire season, the D-backs have hit lefties 78 OPS points below righties, so that would suggest Freeland as the best bet. But Grey performed best of their starters in this series, holding the D-backs to two runs over seven innings, with a K:BB of 10:0. I’d give him the edge for a Chase Field game, and run out this line-up.
- David Peralta*, LF
- Chris Iannetta, C
- Jake Lamb*, 3B
- Paul Goldschmidt, 1B
- J.D. Martinez, RF
- Daniel Descalso*, 2B
- A.J. Pollock, CF
- Ketel Marte#, SS
There is still the question of whether Chris Owings comes back or not - like Mathis, there is apparently a chance he might return in the regular season. If so, then he could replace Descalso. But the question of whether or not he’d be fully up to major-league speed in time for the post-season also needs to be answered. We can’t afford to carry people who aren’t at 100%. To be safe, I’ll assume he and Mathis will not be ready in time for the wild-card playoff.
The bench and bullpen
The standard roster has a seven-man bullpen and five players off the bench. But as noted, that implies a five-man rotation. For a one-game series, there would be four additional spots available.
On the bullpen side, you probably want to have a starting pitcher in there, just in case there’s an injury which requires your starter to be replaced early. Zack Godley and Patrick Corbin would both fit the bill: the former showed today he can dominate the Rockies, throwing eight shutout innings, while the latter’s left-handedness would be as sharp a difference from Zack Greinke as you could possibly want, and also pitched well against Colorado last night.
- Emergency starter: Zack Godley
- Bonus emergency starter: Patrick Corbin
- Left-handed specialist: Jorge De La Rosa
- Charlie Blackmon specialist: Andrew Chafin
- Mid-relief: T.J. McFarland
- 7th-inning man 1: David Hernandez
- 7th-inning man 2: Jimmie Sherfy
- Set-up: Archie Bradley
- Closer: Fernando Rodney
Those are no additional true relief arms, but I can’t say I look at the bullpen and feel there are many more deserving of a slot in there. J.J. Hoover? Jake Barrett? I guess you could add one of those if you wanted, but I feel that any game where we need to turn to them, is not one that’s going well. Better to have a second “relief starter”, in the event we have to use Godley early AND the game then goes deep into extras. If you remember the 2014 AL wild-card game, that did take 12 innings and require the use of 11 relief arms, so we were getting close.
Let’s move on to the bench, where we want a range of late inning replacements for all purposes. Ideally, you’d like a good balance of left- and right-handed bats, offering options for both getting on-base and power, as well as potential defensive replacements and pinch-runners. A third catcher is likely, although with Iannetta starting in this scenario, it’s hard to think of many situations in which we would pinch-hit for him. Here’s what I’d have.
- OF Gregor Blanco*
- IF Brandon Drury
- OF Rey Fuentes*
- OF Jeremy Hazelbaker*
- UT Chris Herrmann*
- C John Ryan Murphy
- IF Adam Rosales
Again, this is dependent on neither Mathis nor Owings being available. Mathis would replace Murphy; Owings would probably take Fuentes’s spot.
That’s a best guess for the one-game scenario. Thoughts, suggestions and comments are welcome, of course!