...based on cumulative QB rating.  He is at 96.1 on the season which puts him at #4 for current starters behind Rivers, Brees, and Warner.  He doesn't have enough starts to qualify and obviously he isn't "one of the best" or anything, but if you look at it that one specific way he has produced overall when on the field.  I say leave the kid in there. 

http://www.nfl.com/stats/categorystats?archive=false&conference=null&statisticCategory=PASSING&season=2008&seasonType=REG&experience=null&tabSeq=0&qualified=false