Sorry, but it doesn't work that way.  While you may be right about TS and PL ultimately not being up to the task of being quality NFL QBs, you don't just throw an undrafted rookie into the starting QB mix 3 weeks before the regular season because he happened to make some plays in the 4th qtr of the 1st preseason game.  It takes more than 3 weeks to groom a starting QB in the NFL.

PL still looks woefully unready (mentally).  Trevor is the man for this season, or at least the start of this season, IMO.  He actually moved the ball with fair success in his 3 series, with drives of 10 plays, 3 plays, and 7 plays.  With very little run game to help him.  

I'm anxious to see Trevor play more in this offense with the (hopefully) improved OL.  And (hopefully) more health than he had last year.