Do you still have Dzeko? If you do, try to sell him, get a new ST, train him one on one scorer because your current Dzeko has corner specialist (which he isn't)
just my suggestion
Ah, yes! I sold the "older" one last season and bought a new one this season. Actually he is a quite good striker/scorer despite the SA (corner.spec). He is current the best assistant in the league and in my team as well. Ivica Olić (SA:shadow striker) at 3rd place.