what is often called FHR problem in this patch isnt in reality related directly to FHR. Its about the anti stun mechanic in PvP (also called diminushing return on stun by blizzard). Stunlock was a key mechanic in pvp, and while it was a bit too strong in 2.3, the complete removal of it in 2.4 made the game much much worse than before for pvpers.
You can find ample explanation about that issue here : 2.4 anti stun mechanic and its impact on PvP
Thats an old topic that was about PTR but pretty much everything it predicted got confirmed by the current patch.
Btw, since you mentioned wowhead, i also wrote a paper about that matter there 