Last week I noted that Nate Silver had expanded upon Bill James' initial work on aging patterns to show that hitters tend to peak between ages 25 and 29, cresting at 26 and 27, with some understandable variations by position. Speed-based players like middle infielders and center fielders peak toward the earlier side of that range, while catchers develop more slowly, and third basemen, who tend to be slower and thicker, peak later and retain a larger share of their value over a longer period of time.
Nate's findings mesh with another concept that James introduced to the masses in the 1982 Baseball Abstract, the existence of a defensive spectrum which runs like so: