In case you skipped the title, the measure here is adjusted OPS (OPS+). These are broken down by ages (20-40), then slammed together into four age ranges (-25, 26-29, 30-34, 35+). These are the hitters who currently qualify for the batting title.What does it tell us? That top-level hitting (150 OPS+ or higher) is strongly correlated in 2013 toward younger hitters, but that teams often carry below-average young hitters (see ages 23-25) either in hopes that they will improve or because they are playing positions at the left edge of the defensive spectrum.
The summary chart shows this a bit more directly. Young hitters are far more likely to be below-average in OPS+ (at least in 2013; we're gonna go back and look at this for past years soon...); players in Age Range 3 (30-34) seem to be around mostly because they can still hit.
Most of these occur in the age 30-32 range, however: when we break out the Age 3 data by 30-32, 33-34, we get 39-17 for the first group, 11-6 for the second group. Even with the selection bias, older hitters (who are still around at age 33-34 because they are supposed to be able to hit, or may have done so in the earlier portions of Age Range 3) are declining relative to league average (70% above the line for age 30-32, 64% for age 33-34).
More on this a bit later....
