JB will be judged by his body of work in terms of wins and losses as well as recruiting and development, which all will include teams and players before and after the tenure of Zak and Derrick. They and this season are a couple data points for him.
But this is the one team that is Derrick's and Zak's with few excuses. They're seniors. Their injuries, while affecting them, were long enough ago that at this point they are who they are for college. They have at least a decent front-court to work with that aren't freshmen.
And I do think the pressure has affected them and the team. They seem to sometimes play not to lose or to just want to get the game over with when they're winning. That's why, aside from winning, the thing I'd most like to see from both of them the last half of this season is to keep aggressive, to play loose -- as JB said in his comments, to do something, even if it may be the wrong thing.