How much should we think about a player's per minute stats versus his per game stats? Dave Berri argues:

Let me close by noting that I don’t think that people should solely look at WP48 or just per-minute stats. If you did that, Jerome James - who posted a 1.341 WP48 - would have been the first half MVP. James, though, only played five minutes in the first half of the season, so his WP48 doesn’t really mean much.

Although I do think people need to look at more than per-minute numbers, I also think people need to stop focusing solely on the per-game stats. Specifically, when we are looking at players who played at least 30 minutes a contest, we shouldn’t penalize players whose minutes are closer to 30 than to 40. Such penalties — as we see in the case of KG — can easily cause us to miss the obvious.

I think the players who are playing at least 30 mpg are exactly the players we should penalize for lower minutes. After all, a great player who offers you 32 minutes per game is genuinely less valuable than a great player who offers you 40 minutes per game. Things like stamina, injury resistance, and ability to avoid foul trouble are all part of what makes for a useful player. It's the players who play less than that who we shouldn't penalize. Of course you don't want to rely on tiny samples like in the Jerome James example, but a guy who's playing well in 15 minutes per game is probably limited to 15 mpg by coaching decisions -- decisions that might be wrong, or might indicate a jam-up of good players at the same position one of whom should be traded -- rather than fatigue.