No they don’t. In arena solo shuffle people go casters like destro lock because they take damage and can’t freecast while being tunnelled. It feels like some attempt to get people to aim at Arms Warriors in the arena meta or something, instead of tunnelling the locks.
This barely even affects casters in bgs where the main threat comes from being locked down from casting when tunnelled, not from lack of armor. But now plate will die faster in zergs to hunters and other plate. Its trashy arena solo shuffle changes.