OPS+

OPS+ (sometimes Adjusted OPS (AOPS) or Adjusted Production (PRO+)) is an offensive rate statistic adjusted for league context and park. Developed by Pete Palmer, OPS+ is the sum of relative On-Base Percentage and relative Slugging Average minus one. The statistic sometimes causes confusion since it is not a simple ratio of OPS to the league average as is the case with many other statistics with the "adjusted" prefix or "+" suffix. Its calculation involves normalizing each of its components to the league average, excluding batting statistics of pitchers.

OPS+ = "OBP+" + "SLG+" - 100

or

OPS+ = 100 *(OBP/LgOBP + SLG/LgSLG - 1)

In the above formula, LgOBP and LgSLG are the league average OBP and SLG (for nonpitchers) adjusted to the hitter's home park, so they may be different for hitters on different teams even in the same league and same year.

For teams and average performers, OPS+ is a fair approximation of runs per out relative to the league average. Its cousin OPS and the expected form for a "OPS+" statistic, OPS/LgOPS, do not result in an estimated unit. From a historical perspective, LgSLG is usually around 1.2 times LgOBP, and so OPS+ essentially is based on 1.2*OBP + SLG. It is therefore more accurate in estimating runs scored than simple OPS, as the best-fit weight for OBP, based on comparison with Linear Weights results is around 1.8.

An OPS+ of 100 is considered average for a hitter. Because OPS+ excludes pitchers from the calculation of league average, however, the average team OPS+, which includes all hitting stats for a team, including those of pitchers, is less than 100.