Monday, November 2, 2009
Why You Shouldn’t Even Consider Starting Chad Gaudin over A.J. Burnett on Short Rest
Although the readers on this site are pretty much unanimous in agreeing with the Yankees starting A.J. Burnett in Game 5 on three days rest instead of Chad Gaudin on something like 20 days rest, in other places the sentiment is a little more mixed. So I figured I should try and quantify it and see if there's any merit to starting Gaudin tonight.As I posted about in this entry, Gaudin averaged an RA of 5.55 over six innings against the Phillies, and the Yankees lost 60.2% of the time when he opposed Cliff Lee.
According to a study done in The Book, pitchers on three days rest were five percent less effective than they were on four or five days rest. I have Burnett's current projection as an RA of 4.06, so if we make him five percent worse, figure he's more like a 4.26 RA guy on three days rest. I'll also decrease his durability rating on the assumption that he won't be able to pitch as deep into the game. And yes, I'm aware that he has good splits in his career on three days rest, but I'm also aware that I trust what rigorous research with the entire population of MLB starters tells us over a handful of starts by one specific pitcher.
So, if we assume Burnett's a 4.26 RA pitcher and pitch him against the Phillies 1000 times, here's how it compares to Gaudin.
| Pitcher | IP | H | R | ER | BB | K | HR | RA | W% |
| Burnett (3 DR) | 6.0 | 6.0 | 3.3 | 3.1 | 2.4 | 5.8 | 1.0 | 4.95 | 46.0% |
| Gaudin | 6.0 | 6.1 | 3.7 | 3.4 | 3.0 | 4.3 | 1.0 | 5.55 | 39.8% |
W%: Percent of games won with Burnett or Gaudin starting vs. Lee.
IMO, that's a big enough difference in win probability to make the idea of starting Gaudin a bad one.
Update: Here's a chart mapping out the full rest of the Series using the two scenarios as suggested by Standard Deviance.
| Gm | matchup | PhIwpct |
| 5 | gaudin/posada | .602 |
| 6 | burnett/pedro | .429 |
| 7 | pettitte/hamels | .478 |
| Phi Series Odds | .123 | |
| Gm | matchup | PhIwpct |
| 5 | burnett/molina | .540 |
| 6 | pettitte/pedro | .455 |
| 7 | sabathia/hamels | .416 |
| Phi Series Odds | .102 |
The last column (Phiwpct) is the Phillies win probability for each game and then the series in total. The first scenario is Gaudin in Game 5, Burnett in Game 6, and Pettitte in Game 7. Burnett and Pettitte get their normal projection since they'd be on full rest.
The second scenario is the one we're looking at right now, with Burnett, Pettitte and Sabathia all on short rest. Their projections are for them to be 5% worse to account for that.
So in the first scenario, the Phillies have a 12.3% shot at the Series, and in the second scenario they have a 10.2%. Further evidence that what the Yankees are planning to do is the right move.
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