A tactic won't help this. I doubt the person who made this thread has the worst tactics on earth, if he was able to get Fernando Torres to sign for him... oO)
Anyway.. Make sure you have him as Poacher or Complete Foward. Make sure your playmakers are set aswell. He can't do much without a good ball too run onto.
Also, go into your tactics screen. Click his name in your team formation. Click 'Advanced' on the bar. And adjust almost every setting to suit him. I do this with Villa, he scores plently and does what he is told..
I doubt this is a lack of form, 1 in 7 is bad. Dzeko on my game is 0 in 4. For both of these guys, this is ****. Anyway.. Try what i said.. Maybe change your team talks.. Or keep praising him, even though he is playing badly.. It will have an effect.