I agree but also agree with Mano that he is improving all the time, one for the future and a very good player.
I can't believe we're on the Man Utd forum, 2nd page of a thread about defenders and nobody's mentioned Fabio?!
I'll mention Fabio. The only man on the planet to rival the awesome hair that is Fabio is Joachim Low.
I thought Fabio was the crap twin, Rafael being the halfway decent one? Anyway, on topic now, i would say Koscielny is underrated more than overrated, as people seem to think he's crap and our defense is terrible, which it isn't. Most overrated defenders are David Luiz, Kyle Walker, Glen Johnson. Never saw the point in defenders who can't defend.
Koscielny is the soldier to Mertesacker's commander. I think he is a typical modern defender, unlike the old school type, fast, hyperactive, good control and passing and can initiate attacks but as a result, compromises his defensive duties which is inevitable. That's why the duo have been doing well. On the other hand, Cahill is a poor man's David Luiz, that says it all. Ok no one rates him highly but why is he England starter.Walker, everyone knows, is a headless chicken.