The Benin international is capable of playing in central or wide midfield roles as well as striker and Bruce has revealed it constantly messes with the way he wants to set up his formation.
"He gives you that good headache where he can play effectively (in several positions)," Bruce said.
"That's what we looked at at the back end of last season when he played up top and got three goals in the last five games, and played in pre-season and got something like three or four goals in five games.
"But you worry and think, 'Can he score enough if we are going to play him up the top end of the pitch?' and that's what I have got in my mind at the moment.
"But he's certainly a very good player wherever he plays."