OPS and OPS+

On-base Plus Slugging (OPS) is exactly what it sounds like: the sum of a player’s on-base percentage and their slugging percentage. Many saberists don’t like OPS because it treats OBP as equal in value with SLG%, while OBP has been proven to be roughly twice as important as SLG% in scoring runs (x1.8 to be exact). However, OPS has value as a metric because it is the only widely accepted statistic that accounts for all the different aspects of offense: contact, patience, and and power. You can find OPS on baseball cards and in broadcasts, and it’s a simple statistic for regular baseball fans to understand.

On-base Plus Slugging Plus (OPS+) has not gained as much widespread acceptance, but is a more informative metric than OPS. This statistic normalizes a player’s OPS — it adjusts for small variables that might affect OPS scores (e.g. park effects) and puts the statistic on an easy-to-understand scale. A 100 OPS+ is league average, and each point up or down is one percentage  point above or below league average.  In other words, if a player had a 90 OPS+ last season, that means their OPS was 10% below league average.

Since OPS+ adjusts for league and park effects, it’s possible to use OPS+ to compare players from different years and on different teams.

Context:

Please note that the following chart is meant as an estimate, and that league-average OPS varies on a year-by-year basis. To see the league-average OPS for every year from 1901 to the present, check the FanGraphs leaderboards.

League-average OPS+ is always 100.

Rating OPS
Excellent 1.000
Great 0.900
Above Average 0.800
Average 0.730
Below Average 0.700
Poor 0.600
Awful 0.550

Things to Remember:

● If you’re looking to evaluate a player’s offense, OPS is a better metric to use than batting average, but should always be used in conjunction with other statistics as well. It’s a good gateway statistic to get people thinking beyond the traditional statistics.

● If you have the choice, use Weighted On-Base Average (wOBA) instead of OPS. OPS weighs both OBP and SLG% the same, while wOBA accounts for the fact that OBP is actually more valuable.

● Since it provides context and adjusts for park and league effects, OPS+ is better to use than straight OPS, especially if you’re comparing statistics between seasons.

Links for Further Reading:

Visually Comparing OPS and wOBA – FanGraphs

Intro to OPS+ – Big League Stew

Baseball Basics: OPS – Baseball Prospectus