Fraction of decisions vs fraction of innings pitched
Posted by Andy on March 20, 2009
So here is the graph that will explain it all:
The red line is the same one we've seen already--fraction of decisions gonig to starters. The blue line is the fraction of innings pitched by the starters. So you can see that it's a very direct correlation. Starters get slightly more decisions than their fair share based purely on innings, and that's because they are automatically the pitcher of record when they start the game. Relievers are only automatically the pitcher of record when they enter into a tie game, more or less. So, in 1988, starting pitchers suddenly picked up a lot more decisions, and it's because starters pitched a lot longer that particular year. For some reason, both complete games and average innings per start were way up that one year.
I'll post some more data related to this stuff on Monday.
March 20th, 2009 at 8:11 pm
I think '88 was a "high strike" year. After the spike-offense season of '87, umpires were supposed to give the high strike call. Bill James famously predicted Danny Jackson's breakout season for that reason. Offense dropped back below where it had been prior to '87.
I thought that as IP dropped, decisions might drop an even greater amount. If anything, it appears IP are falling at a slightly faster pace than decisions.