OPS is one of the most significant statistics in baseball. It means On-base average (OBP) Plus Slugging Percentage. The formula is:

OPS = (H + W)/(AB + W) + Total_Bases/AB

where

Total_Bases = H + 2B + 2*3B + 3*HR

The reason why this statistic is so significant is due to its accuracy in predicting team runs scored. That is, a team's total offensive output for a game or a season very strongly correlates to the team's total OPS.

This statistic is gaining in popularity amongst the baseball powers that be and in ten years time, it will have replaced Batting average as the common benchmark used to rate baseball players.