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March 05, 2002
NOW THAT THE GENTLEMAN HAS
NOW THAT THE GENTLEMAN HAS ASKED: Rob Neyer takes up the issue of whether the long-standing practice of baseball players' editing their birthdays would have a major impact on our view of players' value patterns. Here's what he has to say:
As a postscript, I'd like to address an issue raised by a number of readers, who wondered if all of these bonkers birthdays might have a significant effect on the aging patterns that have been previously discovered by sabermetricians. As you know, it's now generally held that players tend to enjoy their best seasons between the ages of 26 and 28, and that baseball players, as a group, decline after they turn 30. So what does all the new math mean?
Not much. I asked Bill James -- who originated most of this (now) Common Wisdom about ages -- and he replied, "It seems immensely unlikely that this 'deception practice' is going to change anything very much. Even assuming that 20 percent of the players are lying about their age and that the average discrepancy is two years, that only moves the players' primes by .40 seasons, which one would think would have hardly any effect on things like the degree to which a player having his best season at age 37 is surprising. But it's likely that the 20 percent figure is almost totally irrelevant, since the majority of those discrepancies were probably caught and fixed before they were entered into encyclopedias. I doubt that this is much of a factor."
Which is what I figured. When we conduct studies of aging patterns, we're generally dealing with retired players, and the correct birthdays for the great majority of those players are now known.
Posted by Dr. Manhattan at 9:43 AM | Permalink
