The big unknown is how it will affect his performance tonight and in the future. Since starters don’t generally pitch on 3 days’ rest, even the great ones, and even the great ones with bodies that can presumably handle a big workload, we have to assume that it will hurt their performance and/or their chance of future injury.
The Dodgers are up 2 games to 1, so Kershaw is guaranteed to pitch tomorrow unless they win and don’t need him. Conventional wisdom says that you only pitch your ace on 3 days’ rest when his team is facing elimination.
Is that right in this situation? Once we estimate Kershaw’s change in talent, we can pretty much figure out which alternative is correct.
According to The Book, modern pitchers that have pitched on 4 days rest pitched 17 points in wOBA against worse than usual. That is the equivalent of .56 runs in RA per 9. That is a lot. In deference to Mattingly and Kershaw (keep in mind that the pitchers who were studied were also deemed well-suited to pitch on 4 days’ rest, or at least not ill-suited), we’ll make that an even .5 runs. For 6 innings (we will also assume that he will be on somewhat of a short leash after throwing 124 pitches in his last outing), that is a difference of .33 runs plus another .11 runs for that extra inning that Kershaw does not pitch, for a total of .44 runs, or a win percentage of .0044, or 4.4%. So the
Dodgers are 4.4% worse off in game 4 with him pitching then in game 5.
Now let’s do the math. In today’s game, Vegas has the Dodgers as a 67.7% favorite. Presumably if he pitched on 4 days rest, they would be be a 72.1% fave, or a 64.1 % favorite in Atlanta). With Nolasco on the mound, the Dodgers were a 60% favorite in LA, which makes them a 52% favorite in Atlanta.
Chances of Dodgers winning:
1) With Kershaw tonight: .677 + .323*.52 = 84.50%
2) With Kershaw in game 5: .6 + .4 * .644 = 85.76%
So, by pitching Kershaw tonight on 3 days’ rest, assuming that he is .5 runs per 9 inning worse than he would be on the normal 4 days’ rest, costs the Dodgers only 1.26% in win expectancy for the series.
What is the break-even point, in terms of how much worse Kershaw has to be for it to be a tossup? About .22 runs per 9 innings.
For what it is worth, on the broadcast commentary, Pedro was asked about Kerhsaw pitching on short rest. He said that as long as he had time to prepare – to adjust his training routine – that is shouldn’t be a problem. He implied that if it was a last minute decision, then it was problematic. We don’t know how long Kershaw has known or suspected this. Hayhurst (as in our friend Dirk) didn’t think it was a good idea. He called it a “panic” by Mattingly. That is probably a bad choice of words as that would clearly apply to the team that was losing the series.
An astute reader on The Book blog pointed out something which I failed to consider. With Kershaw pitching tonight, Greinke can go tomorrow rather than Nolasco, and Greinke is the better pitcher. (Also, the entire rotation for the NLCS changes, right?)
With Greinke, rather than Nolasco, I estimate the the Dodgers gain 3.7% in win expectancy for that one game, which is a lot.
So now, we have:
1) With Kershaw tonight and Greinke in game 5: .677 + .323*.557 = 85.69%
2) With Kershaw in game 5 and Nolasco tonight: .6 + .4 * .644 = 85.76%
So now it is virtually a tossup! Of course if you use Greinke tomorrow, you have to start the NLCS with Nolasco (then Kershaw and Geinke), etc. If you use Nolasco tonight and Kershaw tomorrow, not only would you get to start the NLCS with Greinke if there is a game 5 in NLDS, but if Nolasco were to win tonight, you can start the NLCS with Kershaw. I am too lazy to see how the different pitching scenarios for the NLCS would pan out and, more importantly, affect the Dodgers’ chances of winning that.