Sunday, August 16, 2009

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.

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