wow.. Tanking is no different now, than it was before. The only thing different now is that you are not over geared for the encounters this time around...

Did you clear T5 in greater than ilvl 80? Then you were over geared.
Did you clear T9 in greater than ilvl 100? Then you were over geared.
Did you clear T13 in greater than ilvl 120? Then you were over geared.