Wednesday, July 17, 2013

Age of a player may vary depending on date v. season.

Ted Williams had the most home runs for a player over 40: 28 in his final season of 1960.  That was something a friend had seen in a newspaper and mentioned a couple of days ago.  Today I ran a query to check, except I couldn't remember it accurately and looked for batters (40 and over), not over 40.  Here is what I found.

Rk Player HR Year Age Tm Lg G PA AB R H 2B 3B RBI BB IBB SO HBP SH SF GDP SB CS BA OBP SLG OPS Pos
1 Darrell Evans 34 1987 40 DET AL 150 609 499 90 128 20 0 99 100 8 84 2 2 6 2 6 5 .257 .379 .501 .880 *3D/5
2 Ted Williams 29 1960 41 BOS AL 113 390 310 56 98 15 0 72 75 7 41 3 0 2 7 1 1 .316 .451 .645 1.096 *7
3 Barry Bonds 28 2007 42 SFG NL 126 477 340 75 94 14 0 66 132 43 54 3 0 2 13 5 0 .276 .480 .565 1.045 *7/D
Generated 7/16/2013.

Then I decided to check their birthdays because I had always thought that Williams retired at 42, not 41.

Evans: Born: May 26, 1947; Final Game: October 1, 1989 (Age 42)
Williams: Born: August 30, 1918; Final Game: September 28, 1960 (Age 42)
Bonds: Born: July 24, 1964; Final Game: September 26, 2007 (Age 43)

baseball-reference.com uses June 30 as the cutoff for assigning an age to a player's season.  If the player's birthday is June 30 or earlier, he seems a year older.  If his birthday is after June 30, he seems a year younger.  See Derek Jeter (June 26, 1974: 39) and Alex Rodriguez (July 27, 1975: 37), only 13 months apart.

Fair enough.  Database work is difficult enough and baseball-reference.com needs to handle this and it's a reasonable way to assign an age to a particular season for a player since June 30 is both half way through the year and the season.  However, baseball-reference.com handles retirement age exactly, using the player's actual age on the day he retired.

Since both Williams and Bonds retired after their birthdays, and because their birthdays are after June 30, their age at retirement is one year older than their age in their final season.

The same seems to apply to a play's age in his first game, his debut.
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1 comment:

Unknown said...

This idea of baseball age turning on July 1 is a big mistake. If you want to know a player's age for a particular year, subtract his birth year from the year in question. That way the year turns on January 1, three full months before the season starts. Thus all players of the same age have more in common than they do when two players born a day apart in the same year have a different "baseball age."

And if you're doing real age-related work, you can use his years+days age if it matters that much.

Wednesday, July 24, 2013 at 12:55:00 AM EDT

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