The OL play is an example of good coaching adjustments. It isn't really that they played a lot better in the 2nd half, though I do think they did. The real difference was the playcalling. The coaches saw that straight dropbacks where our young OL had to block their stud DL was not going to work. Thus, they moved the pocket. Gray started to have a little more success when he got outside the pocket on half-rolls and play action. As I remember, the first play for Shortell was a half-roll as well. This made the OL look better because it simplified their assignments.
Roll-outs simplify things for QBs also, which is what Kill was talking about at the half. The reason things get simpler is that the QB is only working with 1/2 of the field. Sprints, half-rolls, and bootlegs (all of which we saw in the 2nd half) effectively take away the backside of the field and narrow the vision of the QB. The result is an easier set of reads for the QB because he only has to worry about 1/2 of the field.
Now, coaches need to be careful not to roll continuously to one side, as the defense will adjust. They also can't just move immediately on the snap, as the defense will jump the play. That is why you saw some bootlegs (out of the gun, still) mixed in. That way, it looked like they were going one way before heading the other. The simplification is still accomplished, but it keeps the defense honest.
I suspect you will see more of that going forward, especially with Gray in at QB. It stretches the field horizontally and forces the defense to respect his legs. When Shortell is in, and I think he will be, they will stretch the field vertically. He is better at sitting in the pocket, which gives the receivers more time to make double moves (post-corners, out & ups, etc.). That, of course, requires more from the OL.
I'm betting that they will experiment with both QBs over the next three weeks. They are going to want to know specifically what each one can do well so that they can put the QBs in a position to make plays. Same with the OL. They want to see what these kids can do well and want to avoid putting them in a position to fail when the chips are down.