What's a Good OPS?

Many fans like the traditional statistic batting average because they are so familiar with its values.  They know right away that a .300 average is excellent, a .220 average is poor and a .400 batting average is both fantastic and rare.  One problem many fans have when they are introduced to a new measure is that they don't know what values of the statistic are good and bad.  When they hear about OPS for the first time, for example, they might ask: "What's a good OPS?"  

One of the most popular features of my book Beyond Batting Average is a series of simple percentile charts which help give an idea as to which values of a statistic are good and bad by comparing them to batting average.  The table below shows the percentiles for  some of the less traditional statistics and puts them next to the equivalent percentiles for batting average.  This makes it easier for fans to grasp some of the newer statistics.  The chart includes all MLB regulars or semi-regulars with 400 or more plate appearances in 2010.

One can see from the table that the 75th percentile for batting average was .286.  This means that 75 percent of these players hit below .286 and 25 percent hit better than .286.  A player with an Isolated Power (ISO) of .197 would also be at the 75th percentile.  So, we can say that an ISO of .197 is as good as a batting average of .286. Similarly, an ISO of .081 would be bad because it's equivalent to a .243 batting average (10th percentile).  One might also call this a batting average equivalency chart.   

The statistics in the chart can be found on FanGraphs.com. They are defined as follows:

BA = Batting Average
OBP = On-Base Percentage
SLG= Slugging Average
OPS = On-Base Percentage Plus Slugging Average
ISO = Isolated Power = Number of Extra Bases Per AB = (2B + 2 x 3B + 3 x HR)/AB
BB%= Base on Balls Percentage = % of PA resulting in walks
K%= Strikeout Percentage = % of AB resulting in strikeouts

I'll provide batting average equivalency charts for more statistics in later posts.  

Table 1: Batting Average Equivalencies for 2010