In an examination of every player from 1977-2008 Berri found that the average 24-year-old who plays 35 minutes a game is equal to 6 wins per season, After that point, the player's productivity dips. There are exceptions of course, Kobe peaked at 24 (he was worth 15.5 wins a year) but at age 31 this year he's still worth 14.3 wins. Then there is LeBron, last season he played 2/3 of his games at age 24 and was worth a fabulous 27.7 wins for his team.
He's already shown that he's over the hill; this season he's worth a mere 24.2 wins. Pathetic. It's sad when athletes just hang on.