Good rule of thumb:
Keep agility to within 10 of your speed..but the closer it is the more fluid your back will run. Basically he can go fast, but he has the agility to stop and turn on a dime instead of tripping, or needing to stop completely.
A HB will not have a clear lant to the endzone on every play...he needs to make/wait for one.
--Dan
Meat, my goal is 90/90 when my HB gets to the 50s. Right now, at level 34, he is 81/78...with 61 vision.