AL Pitching & defense - 4/20

One of the things that's hardest to do in baseball is evaluate defense. Or, more specifically, to separate defensive contribution to run prevention from pitching contribution to run prevention. Most people recognize, at this point, that fielding percentage tells us, other than in a few extreme cases, very little about defensive performance. One of the things that I like to look at is something that I came up with on my own, independent of all of the other people who came up with it on their own. The main goal of defensive players is, put simply, to turn batted balls into outs. What I've got in the following table is one method of looking at that. Basically, you look at pitching stats, and calculate what the opponent batting average is on balls that were put in play. The formula I use is (H-HR) / (PA-HR-SO-BB-HBP). That misses ground-rule doubles, but for the most part, it identifies which teams are turning batted balls into outs, or failing to do so.

We're very early in the season, the sample sizes are ridiculously small, but there has already been a tendency on the part of some Red Sox fans to swoon over Boston's defense, particularly the infield defense provided by Alex Gonzalez. I don't see it, myself - he's been fine but nothing special to my eyes - but if he's really been tremendous, we ought to see some evidence of it. And certainly the Red Sox run prevention has been excellent so far. But is that pitching or is that defense?

AL Defensive Efficiency

Team	ERA	IP	H	Rank	R	ER	HR	Rank	HBP	Rank	BB	Rank	SO	Rank	GO	Rank	BABiP	Rank
Cleveland Indians	4.87	133	125	2	77	72	17	5	7	11	49	9	90	7	145	5	0.2621	1
Detroit Tigers	4.2	133	122	1	65	62	16	4	6	10	39	6	98	12	164	13	0.2684	2
Los Angeles Angels	4.33	131	138	8	80	63	22	12	5	9	41	7	96	11	148	6	0.2829	3
Toronto Blue Jays	5.52	119	128	4	77	73	24	13	4	3	46	8	85	5	161	12	0.2865	4
Chicago White Sox	4.53	131	136	6	67	66	17	5	2	1	34	3	85	5	143	4	0.2874	5
Boston Red Sox	3.76	134	137	7	60	56	13	2	4	3	34	3	93	8	151	10	0.2952	6
Baltimore Orioles	5.6	143	157	14	95	89	24	13	4	3	69	13	95	10	182	14	0.2975	7
Tampa Bay Devil Rays	6.02	130	153	11	93	87	19	7	8	12	58	11	70	1	149	7	0.3059	8
Oakland Athletics	5.29	131	135	5	82	77	14	3	10	14	50	10	101	13	134	3	0.3071	9
New York Yankees	4.05	120	127	3	63	54	11	1	3	2	36	5	93	8	121	1	0.3118	10
Texas Rangers	4.85	131.67	154	13	75	71	19	7	4	3	32	2	84	4	150	8	0.3147	11
Seattle Mariners	4.99	140.67	150	10	81	78	19	7	8	12	61	12	117	14	155	11	0.3157	12
Kansas City Royals	6.77	117	141	9	99	88	21	11	4	3	72	14	81	3	125	2	0.3235	13
Minnesota Twins	5.75	122	153	11	79	78	20	10	4	3	28	1	73	2	150	8	0.3236	14

To me, that looks like pitching. The defense has been good, 6th best, so far, in the AL in turning batted balls into outs, but I think that the run prevention has primarily come from the pitching staff. They've allowed very few baserunners other than hits (3rd in both BB and HBP), and while they've only been in the middle-of-the-pack at striking batters out, they've been outstanding at keeping the ball in the park (2nd in HR allowed). The defense has been better than average, but, given that they're only 10th best in the AL at ground outs, it's hard to see how you could realistically attribute much of the run prevention to some stellar infield defense...