My opinion, CJ will be a very similar BB to Synjyn Days. He's not as tall as Synjyn, but has a powerful base and big trunks for legs. You will not bring him down with arm tackles, and he's got a great stiff arm. He won't break long runs like Dwyer, but he'll get 3-5 yard pops regularly like Synjyn with 10-20 yard pops a few times per game. It's going to be rare for him to lose yardage.
My only concern with Leggett is his mesh relationship with JT. I honestly can't remember a bad mesh fumble from our QB/BBs this year.