Tuesday, October 2, 2007

Shape stats and consolidation stats

As has been widely noted in the sports media, Jimmy Rollins last weekend became only the fourth Major League Baseball player to join something called the 20-20-20-20 club: at least twenty doubles, triples, home runs, and stolen bases in a season. I think that's great. I've liked Rollins since I followed him through the Phillies system, including catching him alongside Pat Burrell at the wonderful minor league park in Reading, and the 20-20-20-20 thing offers a quick narrative-in-a-number describing the kind of player Rollins has become.

I would contend, however, that joining this quirky "club" should have no bearing at all on Rollins's ranking among players, including his candidacy for the MVP award. The 20-20-20-20 number is what I'll call a shape stat: it describes the shape of Rollins's production, the way his value manifested itself, rather than the amount of value he produced. Homers are worth more than triples, which are worth more than doubles, and all of those are much more valuable than stolen bases. 20 homers and 20 steals is not as valuable as, say, 27 homers and 2 steals; the former totals are just less common. For evaluative purposes, we need exactly the tools that most sportswriters gleefully ignore, the ones such as VORP that assign informed weights to each of these statistics and then sum up the player's performance.

For the purposes of description and narrative, I've got no problem with shape stats. But if we're talking about the MVP or other ways of ranking players, setting aside the shape stats is a good starting point for any serious discussion.