from Amazon
Tuesday, October 11, 2011
Starting Pitcher on a great day v Closer
Max Marchi weighs in with a great article. Read it all. This is the conclusion:
I looked at games played in the past 20 years, thanks to the invaluable Retrosheet data. I selected all the instances in which the starting pitcher has completed eight innings giving up one run at most. These should be the circumstances when the manager can believe his starter “has it” and can complete the game.
I removed the games in which the offense had provided the pitcher more than three runs. Thus, we are dealing with situations in which the game is still on the line, and the manager should be trying to maximize his chances. (In a blowout the skipper’s choices could be dictated by having to rest the bullpen or wanting to try a young arm.)
The games were then split in two groups: Games with the starter beginning the ninth (STARTER) and games with a reliever beginning the ninth (CLOSER).
Here’s how the two groups fared, with more than 1,000 games represented in each group.
runs percentage
allowed CLOSER STARTER
0 76 74
1 14 16
2 7 5
3 2 3
4+ 0 1
Looking at the numbers above, the decision on whether leaving the starter in or removing him appears as a coin flip. However, the above table can suffer from selection bias, with three possible sources of bias coming to my mind.