All our RBs have their warts.
Newby is clearly not built like a workhorse. Personally, I think he'd e better suited as a change of pace guy than a feature back, but he's the most complete guy we've got. He's listed at 5'10", 200, and those are probably generous. You're gonna be waiting a long time to see Newby run like Stewart or Tolbert. They're definitely power backs and he's definitely not.
Imani is a power back, but runs like a bull in a china shop. That's valuable, but he has no lateral agility and no semblance of vision.
Ozigbo has looked pretty gold at times, and pretty mediocre at others. But he spends most of his time on the side of the milk carton.
Ditto with Wilson, which is apparently off the field issues.
The coaches aren't ready to trust Stevenson.
We've been spoiled with AA, Rex, and Helu. What you're seeing is what happens when you have very inconsistent, average at best OL play with RBs that aren't going to the NFL. It's finally come home to roost now that there's no eraser at RB to cover up how much our OL needs to improve. I'm hoping it does (we need to recruit our tails off in the trenches), and the young RBs develop into good backs.