One thing I noticed (that wasn't mentioned by the announcers) on the throw-on-the-run test is that he squared his hips with the line of scrimmage just before throwing. Mechanics like that helps immensely with accuracy.
Years ago, I was watching a McNabb-led Eagles game. The announcers were pointing out that McNabb was inconsistent when throwing on the run, because he wouldn't always square up with the line before releasing the ball. When he did, he was deadly on the run. When he didn't, he wasn't.