The T4 pants are pretty poor. My guild doesn't let prot warriors roll on T4 pants if someone else needs them for their primary spec. The Wrynn greaves are better for sure.
The T4 2 set bonus isn't really good (partly because we have a fairly low parry rate in the first place).
Basically T4 the only pieces really worth considering to get are the shoulders and the bp. Otherwise the helm, gloves and pants are all really outclassed (except for perhaps when you are gearing for avoidance) by their Kara/tradeskill equivalents.
The beast is getting hungrier.