- Cruz has the all-important power factor: consistently hitting the ball hard in the air.
- Cruz does not consistently hit line drives for hits-in-play.
- Cruz does not show consistent plate skills to draw walks and avoid strikeouts.
So our profile is YNN (yes-no-no) in that hierarchical order.
When we apply that profile to our database of 537 relatively successful MLB hitters during the period for which we have batted-ball data (2002-14), we get this distribution of offense measured by OPS:
A normal distribution is in the shape of the famous “bell curve” and it indicates that outcomes will gravitate around the mean (the peak of the curve) and that variation from the mean will fall mostly within one or two “standard deviations” from the mean. More specifically, 68% of the outcomes will fall within one standard deviation of the mean and 95% of the outcomes will fall within two standard deviations.
The fact that we can get a normal distribution within each subcategory indicates that we’re doing a decent job of narrowing down the variation to the more “random” factors.
So what do we learn about Nelson Cruz?
Among those with Cruz’ skill-set (Power: yes; Line Drives: no; Plate Skills: no), the mean is .754 OPS and the standard deviation is .051. That means the great majority of players with that skill-set will fall between .703 and .805 in OPS.
As we can see, Cruz is at .829, which is one-and-a-half standard deviations above the mean.
To date, then, Cruz has “out-performed” the typical “one-dimensional power guy” by a fairly considerable margin, but not so much that he’s “off the curve.”
Will he “regress to the mean”?
To get at that we need to go a bit deeper. Has he been lucky or good or both?
Part 3 here.