Wyers: How much team age matters

From SABR member Colin Wyers at Baseball Prospectus on September 5, 2012:

One thing sabermetrics does very well is examine previously held conceptions about the game objectively and quantifiably.

What I want to examine is how age affects how we project a team’s performance going forward. The common assumption is that, all else being equal, being young is better than being old. A young team has promise yet unfulfilled, while an old team is on the decline and needs to consider rebuilding. But is this really true? And how much does it matter?

I took all teams from 1950 on and figured their winning percentage and the age of their batters (weighted by plate appearances, omitting pitchers hitting) and pitchers (weighted by innings pitched). Then I found the record of the franchise over the next five seasons (counting a team’s results even if it changed names or city in the interim, figuring that roster constitution is more vital than geography or nomenclature for our purposes here). Then I ran an ordinary least squares regression to see how these factors worked together to predict future wins. (The results were similar when I limited the scope of the study to the next three seasons.)

Read the full article here: http://www.baseballprospectus.com/article.php?articleid=18232

Originally published: September 5, 2012. Last Updated: September 5, 2012.