I did something similar in December called How Well Might Pujols Hit After Age 35? It seemed like the odds were against him doing well after 35. Here what I did was to find the top 27 players in WAR under age 32 and then see how much WAR they got over age 35.
In the table below they are sorted from highest to lowest in over 35 WAR. I don't have numbers for AROD or Pujols over 35 yet. So for the other 25, they averaged 13.4 WAR over age 35. As you can see, though, there is quite a distribution and Bonds must affect the average quite a bit (it is 11.67 without him).