Play action passing

Everyone's favorite site PFF has an interesting look at QB performance when using play-action passing.  Of 38 qualifying QBs this year, the 2 QBs with the worst QB rating when using play-action:  John McCown and Mike Glennon.  The 2 QBs with the biggest drop-off in completion % between non-play action and play action:  Josh McCown and Mike Glennon.While the offense doesn't use a lot of PA (McCown had the lowest % of PA passes and Glennon's % wasn't much more significant), I'm surprised it's not more effective when we do use it considering how much we try to force the run, at least early in the game.