I am aware of his good stats, but I think he sometimes gets them by running into areas he shouldn't (have to) cover, and sometimes what he does just doesn't seem to matter.
I didn't check if it's still the case but earlier this season United had the most high turnovers in the PL (I think that was the stat) and Bruno's defending/pressing was quite crucial to get those. And still United failed to score goals from these. For me this can be explained to a certain degree by Bruno's pretty wild positioning, his movement just isn't connected to that of most of the team.
Or in other words, if he wins a ball high up, has to try a Hollywood pass to another player who is just to far away from him to play it simple, and misplaces that, than it was a lot of effort and a good defensive action.
Yet the benefit for the team is the same as when he had just stayed in formation and didn't run to win the ball.