It's amazing that you all can tell so much from one drill.
What I took away from that drill is that Williams is most comfortable with Coley and therefore that pass was right on the money. It also looked like Coley ran by far the best route because he kept his eyes upfield until it was time for the break instead of trying to look back early and sliding outside as a result.
I played intramurals in grad school with a former nfl quarterback (albeit a practice squad guy). I remember being surprised at how tough, even for him, it was to get down the timing of a back shoulder throw on a vertical route. I am certainly no expert, and wouldn't mind Olsen starting, but it seems like those throws are the type of thing that gets nailed down during the dog days of summer, after the offense has been installed in the spring and when the qbs and receivers are out practicing routes and timing for hours a day (a guy can dream, right?).