Now that we’re moving on from the introductory metrics, let’s dive into an offensive stat that is slightly more intricate, called OPS+.
OPS+ is similar to “OPS”, except it adjusts for certain factors which allows it be a more accurate statistic of evaluating a hitter. Adjusted metrics like OPS+ help evaluators put a player’s contribution in the right context.
OPS+ Explained
OPS+ takes a hitter’s raw OPS, adjusts for ballpark factors and scales it to the league average. This is important because it helps us more accurately compare players across different teams, leagues, and years.
It is represented by this equation:
OPS+ = (OPS / league OPS, adjusted for park factors) x 100
OPS+ is extremely simple to interpret. Since the metric scales the league average OPS to 100, each percentage point above or below represents one percentage point above or below the league average. In other words, if a hitter has an OPS+ of 120, that means they were 20% better than the league average. Alternatively, if a hitter had an 80 OPS+, they were 20% below the league average.
Looking at a different example, a hitter with an .800 OPS, but plays their home games in an extreme hitter’s park might be less valuable than a hitter with the same OPS who plays their home games in an extreme pitcher’s park. Adjustments like this are important because we want to know how much hitters are affected by factors that are out of their control.
Along the same logic, hitters with similar raw OPS numbers in different eras may grade out differently by OPS+. This comes into play when comparing the careers of two different players, especially when it comes to hall of fame debates. For example, a hitter with an .800 career OPS in the late 90’s may not get the same accolades as a player with the same OPS in a lower run scoring era in baseball history.
OPS+ does a better job than its predecessor OPS by putting performance in context, and moves us one step closer to more accurately evaluating big league hitters.
Summary
Understanding how and why we look at weighted stats is critical to improving our methods for comparing offensive value across different eras and seasons. At the end of the day, when we use these types of metrics, we want to incorporate all relevant factors to ensure we are making the best possible summation.
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