Why did Andrew Bailey's ERA double in 2011?

Andrew Bailey / Icon SMI

The Red Sox's new closer, Andrew Bailey, has some interesting numbers in the last couple of years. He pitched 49 innings in 2010 and 41.2 last year. His BB/9 IP was similar both years (2.4 vs 2.6). His hit rate got a little worse (6.2 to 7.3) and his strikeout rate got a little better (7.7 to 8.9). So, why did his ERA climb from 1.47 to 3.24?


In each of 2010 and 2011, Bailey allowed 3 homers. They were all solo shots except for a 2-run walk-off homer by Josh Hamilton on 7/9/2011. So that account for just 1 of those extra runs.

The real issue was the fact that he allowed more hits (and more hits for extra bases) in 2011 when runners were on base.

Here were his splits pitching with runners on base:

Year	PA	H	2B	3B	SB	BA	OBP	SLG	OPS	GDP	BAbip
2010	84	11	1	0	3	.147	.183	.160	.343	4	.196
2011	67	16	4	1	5	.271	.333	.424	.757	3	.375
Career Total	289	46	6	2	9	.180	.240	.255	.495	10	.238

Provided by Baseball-Reference.com: View Original Table
Generated 12/28/2011.

In few plate appearances in 2011, Bailey allowed 3 more doubles, 1 more triple, plus that homer mentioned above. His OPS+ with runners on was .343 in 2010 and a staggering .757 in 2011.

The good news is that the increased XBH in 2011 were likely due at least somewhat to random chance, as shown by the really high BAbip, and things should regress toward the mean to some degree in 2012....or at least the Red Sox hope that's what happens.