The other two, ok, sure, but then again Luke Staley might like a word. Sure, he ran for more yards as a sophomore, but it was still less than 500 total and his YPC dropped from 4.7 to 3.7.
Katoa showed promise as a freshman. No idea if he'll ever have a thousand yard season, but seems a bit unfair to already rule it out.
Ty'son has all the physical tools to be a thousand yard back. For various reasons, it hasn't happened yet. That said, I believe he's walking into the best situation of his college career. BYU is expected to have a solid offensive line, and he's never had that in college. There could arise another reason he doesn't do it this final year for him, but the opportunity is there to finally live up to his very high potential.
I don't know much about Esupka, but I'm glad we've got him. He could surprise me and beat out the other two for the starting role, but at the least he's a solid RB and a solid third option when we need it, and history says we'll most likely need it.
I don't see any of these guys suddenly breaking out for 1582 yards and an 8.1 ypc, but I'm very happy we've got all three. They're all at least solid, and that alone will make Zach's life easier than it was initially looking like this year.