Note: Posada's WAR in the season following last >3 was actually two seasons later as he was injured for most of the subsequent season
In Table 1 above, we see that Johnny Bench and Carlton Fisk not only had the most years with a WAR greater than 3 (what I will consider “productive” for this exercise), but also peaked at the earliest age of this group at 24. We also see that when a player last managed a WAR greater than 3, the subsequent season their WAR decreased significantly.
Table 2 shows the last time the player caught at least 100 games and his WAR that season along with the following season’s WAR. It becomes evident that once a player last caught 100 games in a season his production started to deteriorate rather quickly thereafter and retirement was right around the corner.
Based on what we have seen from Posada this season to date (-0.3 WAR), it can be inferred that both age and catching, has worn him out, likely to a point that he may never regain his previous level of productivity.
There is no doubt that Posada has had a productive career. At the same time, he had very few seasons where he was the “best” catcher in the game and he also did not accumulate as many productive seasons as the others. P osada should not get much credit for the Yankees post-season success; his World Series numbers are awful. He had a larger part in getting the Yankees to the post-season but their success in the playoffs did not hinge on his productivity.
Posada was a very good player, but never spectacular, as I think Hall of Famers should be. The contention that Posada is a "borderline" Hall of Famer is valid. However, he comes up short when compared to the great catchers in the Hall of Fame. I would not cast a vote for him.