Laskey is proven. He is gutsy and explosive for short yardage. He also has shown he can catch passes thrown to him. Custis is not proven at this time, but that does not mean he can't do the job. I certainly hope we have more potential B-Backs than this. Redshirt players often fill in nicely and sometimes even better than the previous players, so there is hope for all the backfield positions. I believe Perkins will do well at A-Back. Game exposure does wonders for some players. Playing more this year may bring out the best in some of last year's reserves.
Speed is really needed for the A-Back positions, but, personally, I also like to see an A-Back explode into the tacklers. Often, an explosive back can burst through the crease between two tacklers if he uses strength and another gear. The situations where the defenders have been blocked out of the play is fine, but often the back has to create his own yardage to keep a drive going. Personally, I detest seeing a back or quarterback go out of bounds when he could cut inside and gain a few extra yards.
However, the effectiveness of the option depends on the actions of the quarteback. Either the coach must use a quarterback adept with the option or change the offense to the talents of the non-option quarterback. If this is not done, it will make little difference who plays A-Back or B-Back.