Normally, I'd agree. But a few series in the preseason (if he's not starting the regular season, you have to give the majority of reps to the guy who is) and a game or two at the end of the regular season probably isn't enough to address the point raised by
@Phills14 -- we need to know whether to go all-in for a QB next year. As you pointed out, one or two games wouldn't give the rest of the league a chance to adjust to him.
I'm not saying to toss him in there no matter what, but I think they need to go with whomever they think gives us the best chance to win, and just see how that guy does. Next year's draft may well be the most important one this franchise has seen in a long time, because we'll have the assets to make a move if we need to. And we
must know whether or not we need to make that move.