From what I saw out of the guy, there was nothing that he did wrong. He was able to escape from the pocket when it broke down and then get rid of the ball. He could hit deep passes (although of course the receivers could not catch it). He made good decisions. Everything looked very good.
The issue of him going against the 2s and 3s is not as big a deal in evaluations as it is for other positions. If you're evaluating an O-lineman in the second half of a preseason game, you have to take into account that the level of competition is slower and weaker. But for a QB, the physical strength of defenders is not really an issue... it is really just an issue of the speed of the game.
The second issue in evaluating this kind of action is of course the scheming, or the lack thereof, in a preseason game. Although from what I could tell, the Colts were putting more effort into gameplanning than the Rams were (from what I've picked up on, sometimes teams with a new HC and regime will lean toward doing this, and sometimes they won't).
Ultimately there was nothing that Davis could have done differently to perform better. The issue of playing 2s and 3s, and the issue of scheming, is nothing more than a new obstacle for him to face later on rather than an indication that he had failed any test that was before him. A performance like this in a preseason game is much easier to evaluate than looking at a young, unpolished QB in college with talent on the field that on average isn't worthy of a spot on a 90-man roster and running schemes that are often times irrelevant to NFL play.
It is probable that the Rams will hold onto him, since Fisher & Co are the ones who brought him in, and he is a good insurance policy if Bradford either gets injured long-term or fails in this make-or-break year.