The suggestion that Williams has proven "nothing" is total nonsense
To say that a guy who has averaged nearly 5 per carry (4.84 to be exact) against an SEC schedule in the past two seasons over 165 carries has proven "nothing" is nonsense.
Getting the offers he got by itself is proof of athletic ability. Carrying the rock 165 against SEC defenses and coming up just shy of five YPC is plenty of proof that the dude can compete against high caliber talent.
Does it mean he's going to absolutely be RB1 this year for us? No. Does it mean he's going to remind us of the last Williams at RB? Maybe not.