You gotta be pretty damn bad to get solo'd by a Feral. Counter his Berserking / Incarnation with your CDs then enjoy 2.5 minutes of wet noodle damage without MS or good lockdown. The only way a Feral is putting out any pressure on his own when his CDs are down is when he successfully interrupts on CD so his Tiger's Fury is constantly reset through the PvP bonus.
As for DK: Maybe if stars align? Haven't played mine this addon but I can't recall my healer ever dying to one 1v1 in 2s (at 2.2k MMR first day of the season) before like 40% dampening.
Rets can't solo any semi-decent healer. They have strong burst and good utility but they're reliant on their 2 minutes burst CDs (see: same CD as trinket, same/higher CD as many defensive cooldowns) and have much lower lockdown compared to Rogues as well as no MS.
Just to clarify here, I'm not saying the game is balanced outside of Combat Rogues whatsoever, but I get the feeling most if not all players defending that spec are completely delusional to what state this game is currently in.