Kurt Warner, playing against a defense that put no pressure on him and inexperienced DBs playing 10 yards off the ball: QB Rating 115.9
What does this prove?
It proves that, with time to throw, Kurt Warner can still be a very effective QB. In fact, if he was on a team that consistently protects the QB, I'd say he could lead a very successful team as a starter.
That said...
Marc Bulger, playing against a defense that was blitzing him constantly and with success due to poor blitz pick-ups: QB Rating 134.7
What does this prove?
It proves that the Rams picked the right QB.
That said...
Bulger left the game with an injured shoulder and will likely miss a block of games for the third time in 2 years.
What does this prove?
It proves that until the Rams find a way to balance their playcalling in a manner that keeps the defense from sending everyone to crush the QB, no QB will be safe in this offense.