So, first, I never said they didn’t raid. I said they didn’t actively raid.
Secondly, of course players with T3 would dominate in BGs - it was literally the best gear in the game at the time for most classes/roles. That’s like saying a level 85 dominates level 20 BGs.
A player with T3 could step into PvP for the first time and likely come out the winner without much trouble.
And if memory serves, the Rank 14 grind came before Naxx.