I'm sorry, but right now Kolarov is playing much better than Clichy. They're both pretty poor defensively but at least Kolarov provides a genuine threat offensively.
Just because Clichy is quick doesn't mean he's better. He is a very poor crosser and other than his pace, the only thing he has over Kolarov is that he's slightly more composed on the ball, but then again, he never really tries anything adventurous with it.
With regards to Dzeko, his goalscoring has been fine, but his overall play hasn't. Admitted, he is an easy target, as, as soon as he makes one mistake people note it. A prime example would be at a game: Dzeko loses the ball - "for fucks sake Dzeko, get hold of it" which after a few more times "he's a fucking donkey/cart-horse". Whereas if say Aguero loses the ball you wouldn't hear anything or would hear a "come on Serge, get it under control" kind of thing, and if it continues it'd just be accepted he had an off day.
Although Dzeko does have an off-day more often that any other striker, I do feel the atmosphere within the crowd/the team itself adds the pressure on him not to fuck up. Not the rotation.