Well, Steve over at WasWatching had a slight problem with their methodology – and rightfully so. As he said, “A few old apples can easily ruin the average of the whole barrel” which is absolutely valid.
Furthermore, it does not consider each player’s impact. Should a 42-year old bench player have the same value as a 22-year starting second-baseman? Clearly no, and this tries to fix it.
I’m not even sure if this is solving the problem, but I gave my own go at trying to evaluate whether the Yankees got older or younger. I just basically evaluated the Age/Plate-Appearance and Age/Batter-Faced between 2005 and 2009.
Basically what I did was this:
For batters: Multiply the player’s age by plate appearances; sum all of these up for the entire team; then divide by the total plate appearances for that team
For pitchers: Multiply the pitcher’s age by batters faced; sum all of these up for the entire team; then divide by the total batters faced for that team.
For all the exact data, take a look at the spreadsheet at Google Docs.
Basically, using this method the following data was determined.
The average Age/PA for the hitters in 2005 was: 32.69.
The average Age/PA for the hitters in 2009 was: 30.69.
The average Age/BF for the pitchers in 2005 was: 34.05.
The average Age/BF for the pitchers in 2009 was: 29.07.
So yes, under Brian Cashman, the Yankees have clearly been getting significantly younger – especially the pitchers.