Barry Bonds had a backwards career. The chart will make that make sense. Bonds aged in a peculiar way: he got better with age, much better.
Below is the hitter aging curve plotted with Bonds' career incline. The red line, labeled “Bonds,” begins Bonds' career with a reset rating of 1509 at age 21, which starts him on the aging curve. His career diverges more and more as he gets older, finally he retires with an RVL of 93 at age 42, which is about 135 rating points higher than average rating of 41 year hitters. There aren't enough 42 year old hitters to even make a meaningful comparison.
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The yellow line shows Bonds' career with his age 42 rating swapped with his age 21 rating, his age 40 rating swapped with his age 22 rating, and so on. This curve is then shifted down so that the new rating for Bonds at age 21 matches the overall hitter aging curve rating for age 21. The path of the yellow line follows the overall aging curve more closely. It even looks like a realistic career path for a Hall-of-Fame player, what with a huge incline in ability early and a very low end point, which points to the fact that the whole curve was likely shifted downwards to match the player's rookie rating to the hitter aging curve.
Bonds' reverse curve looks like Ken Griffey's regular curve. Bond's career path looks like water running uphill. If Bonds wasn't using performance enhancing drugs after age 34, something very strange must have happened to him.
Post 226 contains an explanation of the hitter aging curve.