Allow me to re-FIFY.
"One practice throw does not a career make."
I remember the throw to Hines as I was at the game... it was a beautiful throw. Driskel's issue was less his throwing ability and more his decision making ability. I also don't think anybody is looking at this one throw and saying we have a Heisman winner at QB.
The bottom line is that it is pre-season. Fall Camp has started and seeing our QB make a nice throw in the rain after the QB play we witnessed at the end of last year gives everybody hope that we may be good this year.
I think Del Rio is going to be very good (mostly because his performance in the Spring Game). I don't think he will be a Heisman guy, but I think he will manage and execute in the offense very well and make good decisions. There are enough play makers that if he can get the ball out quickly to the right guy our offense could be very good. I still remember seeing guys running wide open during the Bama and FSU games and if we only had a QB that could make decisions and throws those games could have been different.
I realize you are trying to temper expectations, but dude... it is Fall Camp... and we finally get to see a little glimpse of football. Let us enjoy it.