I think what people used to do was take a 15mpg scrub, extrapolate to 48 minutes, and try to determine what value he was. Problem was with these guys you'd end up with 11 fouls or 17 turnovers per game.

What some brought up was nobody really plays 48 per game so they started the 40mpg comparison and then the 36mpg is the new standard because your average starter plays about that.
Thing is, unless you're really young, there's a reason you're only playing 20mpg off the bench: You stink. Your 20mpg numbers will never match your extrapolated 36mpg numbers. So what's the point. Besides, you're now playing against starters and not backups so you will take a hit there as well.
It's a pointless idea.
...as to the recent tone of this thread you don't compare Nate to Sessions. You compare Sessions to Duhon when trying to make a decision. Nate has nothing to do with Sessions. Duhon does.
In that, simply put.
Sessions is quicker and more creative.
Duhon is a better defender and a better shooter.
So how much are we gaining here? Not enough for me to lock up Sessions for five years I can tell you that much.
There are reasons why only the Knicks, Clippers, and Bucks care about him. In fact, the Clippers don't seem to care anymore and the Bucks are just waiting to see if the Knicks overpay for him or not. The Knicks are waiting to try to dump Jeffries before they even bother.
Does this all really add up to a must have player? A guy you pencil in as the starting PG, wipe your hands, and muse you're done with the PG position for the future?
I don't think so.
If this is all that's to be had you retain Lee and Nate for one more year and worry about it all next season and let Sessions go sign for 3M back in MIL.
We don't need another Jared Jeffries!