Huffington Post: Bradbury: Is Your Favorite Free Agent Over the Hill?

If you follow sabermetrics, you’re probably familiar with the notion that the peak age for baseball players is 27. If this is the case, then the best players are several years past their prime. What does this say about how they’ll perform during the long-run contracts that top free agents typically sign? For example, last year’s top free-agent pitcher CC Sabathia will be seven years past his hypothetical prime once his contract expires when he’s 34.

There is no doubt that age will sap players of their ability over the course of most free-agent contracts; however, the decline isn’t as pronounced as many people believe. In a recent study, I examined the playing careers of many players over a span of 86 seasons to see how players aged. After controlling for a multitude of factors that might affect player performance I found players peaked around 29—-and this holds for hitters and pitchers. And I’ve proposed some explanations as to why past studies have found lower peak ages.

More important than the later peak is the fact that the rate of rise and decline is not all that pronounced. Though old players may not be what they once were, the evidence indicates they can still be valuable. Players are who they are, and will perform slightly better and worse than their peaks from their late-20s through early-30s. I find that players perform within two percent of their peaks from ages 26 to 32. Extending beyond this range, the dropoff isn’t particularly steep. According to my estimates, a hitter who has a .900 OPS at his peak would be expected to post around an .850 OPS at 35; a pitcher with a peak 3.5 ERA is expected to post around a 3.75 ERA at 35.

Thanks to Acres.