I agree with pete0. Yes, Gana is full of energy but that energy is rarely being used for anything positive. Gana seems to like to precheck opponents but leave the player he was supposed to mark/cover. And that creates possibilities for the other team.
If anything he's a luxery-player and as most have realized by now (about bloody time too), playing two defensive midfielders does not work. It didn't work during Martinez, it doesn't work under Koeman.