Using the slow off hand is causing you energy Regen issues not low haste.
Never understood why people don’t grasp basic class and spec mechanics, you’re getting what maybe 500 extra damage on an offhand hit (already reduced) at the expense of less autos and energy for force slowing your auto reset? Also way less passive CP gen which is why you’re starved.
Also, per your example frost dk is linear, and is in fact the second to or the least effective melee spec in the game. Former dk main, plays at 2200 no voice in reg 3s last expac with random lfg players.
Sub and outlaw issues are raw tuning, simply put too many nerfs. The 7 combo point sub is the smoothest iteration of rogue I’ve ever played because you have a safety net on overcapping from random white hit attacks. Same with outlaw. Buff base damage if abilities and the specs are fine. Much like dk, rogue seems to be balanced for PvP by how it feels to play into instead of how it is to play which is flat wrong.
Assassination needs a tree rework. It’s not my favorite spec, that would be sub. However sub and outlaw trees make a hell of a lot more sense than assassination.