OPS + and ERA + - Park independent stats

Sunday August 16, 2006

I know this is bout a week behind, but I thought it was an interesting study of how teams hitting and pitching was doing independent of the park they played in and how it related to win/loss.

I don't think that 8 games has changed these stats that much.

At the bottom of the page are the definitions and links to The Hardball Times.

American League
East	W	L	Pct	GB	OPS+	ERA+
New York Yankees	67	42	0.615	--	117	100
Boston Red Sox	62	46	0.574	4.5	100	113
Tampa Bay Rays	60	49	0.55	7	106	109
Toronto Blue Jays	52	57	0.477	15	101	104
Baltimore Orioles	46	64	0.418	21.5	93	92
Central	W	L	Pct	GB	OPS+	ERA+
Detroit Tigers	58	50	0.537	--	94	109
Chicago White Sox	56	54	0.509	3	93	112
Minnesota Twins	53	56	0.486	5.5	106	89
Cleveland Indians	47	62	0.431	11.5	100	89
Kansas City Royals	42	67	0.385	16.5	87	93
West	W	L	Pct	GB	OPS+	ERA+
Los Angeles Angels	64	43	0.598	--	107	94
Texas Rangers	61	47	0.565	3.5	100	106
Seattle Mariners	57	52	0.523	8	91	109
Oakland Athletics	48	61	0.44	17	90	93
National League
East	W	L	Pct	GB	OPS+	ERA+
Philadelphia Phillies	61	46	0.57	--	103	100
Florida Marlins	56	53	0.514	6	94	98
Atlanta Braves	56	54	0.509	6.5	97	111
New York Mets	51	58	0.468	11	94	97
Washington Nationals	38	72	0.345	24.5	100	85
Central	W	L	Pct	GB	OPS+	ERA+
St. Louis Cardinals	60	51	0.541	--	96	110
Chicago Cubs	57	50	0.533	1	89	116
Milwaukee Brewers	54	55	0.495	5	99	87
Houston Astros	54	55	0.495	5	95	96
Cincinnati Reds	47	61	0.435	11.5	80	100
Pittsburgh Pirates	45	64	0.413	14	92	92
West	W	L	Pct	GB	OPS+	ERA+
Los Angeles Dodgers	67	43	0.609	--	103	115
Colorado Rockies	60	49	0.55	6.5	98	108
San Francisco Giants	60	49	0.55	6.5	82	124
Arizona Diamondbacks	50	60	0.455	17	92	106
San Diego Padres	46	65	0.414	21.5	91	82
Adjusted OPS+				From Baseball Reference
1. Compute the runs created for the league with pitchers removed (basic form) RC = (H + BB + HBP)*(TB)/(AB + BB + HBP + SF)
2. Adjust this by the park factor RC' = RC*BPF
3. Assume that if hits increase in a park, that BB, HBP, TB increase at the some proportion.
4. Assume that Outs = AB - H (more or less) do not change at all as outs are finite.
5. Compute the number of H, BB, HBP, TB needed to produce RC', involves the quadratic formula. The idea for this came from the Willie Davis player comment in the Bill James New Historical Baseball Abstract. I think some others, including Clay Davenport have done some similar things.
6. Using these adjusted values compute what the league average player would have hit lgOBP*, lgSLG* in a park.
7. Take OPS+ = 100 * (OBP/lgOBP* + SLG/lgSLG* - 1)
8. Note, in my database, I don't store lgSLG, but store lgTB and similarly
OPS+ (Link)	From THT
OPS measured against the league average, and adjusted for ballpark factors. An OPS+ over 100 is better than average, less than 100 is below average.
ERA+ (Link)	From THT
ERA measured against the league average, and adjusted for ballpark factors. An ERA+ over 100 is better than average, less than 100 is below average.