On base percentage plus slugging percentage (OPS) is a relatively new measurement of a hitter’s performance in baseball. It essentially measures the player’s ability to hit the ball, and also to get safely to base. Thus many look to OPS as a valuable tool for assessing the offensive skill of a player.

The on base percentage is a measured by the sum of hits (H), walks (also called bases on balls or BB), and the number of hits by a pitch (HBP) divided by the sum of times at bat (AB), (BB), sacrifice flies (SF), and HBP. The formula looks like this:

H + BB + HBP/ AB + BB + SF + HBP

The other part of OPS is slugging percentage, which measures the number of types of hits like singles, doubles and triples, divided by the times at bat. TB stands for total bases and the total formula for calculating OPS is the following:

AB(H + BB + HBP) + TB (AB + BB + SF + HBP)/ AB(AB +BB + SF + HBP) = OPS

Generally the OPS of a good player is considered to be around .900 to .950. An OPS of 1.000 is generally the high standard for an exceptional player. OPS of 1.000 or higher is scored by the baseball greats. For example, Babe Ruth has the highest career OPS at 1.1636. He is followed by Ted Williams and Lou Gehrig.

Barry Bonds stands fourth in the rankings for career OPS with a 1.0533 measurement. However, Bonds may surpass Williams, Gehrig, and Ruth when he ends his career, since his OPS is quite high seasonally. He has the two top-rated seasons for OPS.

Some critics feel that the OPS is not a great formula for measuring performance. They feel that the on base percentage is nearer to the mark than the combination of on base percentage and slugging percentage.

Criticism stems from the fact that slugging percentage and on base percentage are given equal status in OPS. However, on base percentage tends to more accurately indicate the likelihood that a player will actually make it to the home plate and score a run. In fact on base percentage tends to be about a 10-25% lower than OPS.

OPS was first established in the 1980s, so it is a new way of evaluating offensive skill. It is a popular measurement for baseball fans. However, it may not be given as much credence by coaches when assessing value of an individual player.