Using the Start Log, we can track how the bullpen is doing this year based on the game’s starting pitcher. Here’s how things look so far (the starters are ordered by the average number of innings the bullpen has thrown in their starts):
|Starts||Total IP by
Pen in starts
|IP per start||Pen ERA||Pen Ratio||H/9||BB/9||SO/9|
So, for example, Kendrick has made four starts on the year. In those starts the bullpen has thrown 21 innings, which is about 5.25 innings per start. In those 21 innings they’ve thrown to a 2.14 ERA and a 1.43 ratio while allowing 9.43 hits per nine innings, 3.43 walks per nine innings and struck out about 7.71 batters per nine innings.
Important to remember is that some elements of how many innings the bullpen pitches in a start by a particular starter is out of that starter’s control. For example, the bullpen has thrown 28 2/3 innings in the 14 starts that Halladay made, but 12 of those innings came in a May 25 game against the Reds that went 19 innings. Despite that, the pen has still thrown the fewest number of innings per game when Halladay was on the mound. Excluding the May 25 game, they have pitched 16 2/3 innings in his 13 starts or about 1.28 innings per game.
Overall, the pen has thrown an average of 2.75 innings per game for the year. They have thrown less than that in the starts by Halladay, Hamels and Lee and more than that in the starts by Oswalt, Worley, Blanton and Kendrick.
In the games where Lee or Hamels was on the mound, the pen has 1) thrown to a better than average ERA 2) thrown to a better than average ratio and 3) struck out batters at a rate that’s higher than average for the year.
In the games started by Blanton or Worley, the pen has been worse in all three of those categories.
That leaves Kendrick, Oswalt and Halladay. With Halladay on the mound, the pen has thrown to a slightly higher than average ERA but was better in the ratio and strikeout categories. With Oswalt on the hill they’ve struck batters out at a lower rate, but pitched to a better than average ERA and ratio. In Kendrick’s starts they’ve struck out more batters than they have on average and thrown to a better ERA, but with a higher ratio.
Finally, if you look at the runs allowed per inning pitched for the year based on the starter who started the game, it’s easily to see who has gotten the best performance from the pen:
|Starter||Runs allowed per inning by pen|
Remember there that we’re looking at runs allowed per inning by the pen and not earned runs. So the pen has a 2.14 ERA in games started by Kendrick, but three of the eight runs the pen has allowed in his starts are unearned. So the pen has a nifty ERA in his starts, but the runs allowed per inning pitched is much worse compared to the rest of the group.
Anyway, it’s clear that Hamels is the big winner of the best bullpen performance so far award. Relievers have allowed just five runs in 29 innings in his 13 starts for the year.