The very fact you're comparing his form under Pearce with his current form kind of shows you don't know what you're talking about here. But that's fair enough, in a way, if you don't follow City or Ireland, he could easily slip under your radar, he gets so little credit in the media.
He's come on in leaps and bounds these last couple of seasons (mainly because he's sorted his life out, off the field) and is one of the best central defenders in the league now.
Where would I rate him?
In order:
Rio
Carvalho
Vidic
Dunne
Toure
Terry
Carragher
Wes
Agger
Skirtel
Woodgate
Gallas(on current form)
Laursen
Distin
When it comes to Dunne/Toure/Terry/Carragher, they are all very close though but I'm gonna stick Dunne at the top, cause I can