So I was reviewing the destro changes for locks lately after the ruin/devastation change, and did some thinking.
It seems that PVE locks are just fine with ruin being a 5 point talent, as it helps with their stat (crit) scaling for raids. It's a better 5 point investment as an 11-15 point talent sink than just 5% crit (which is the current 21 pointer). This leads me to believe that, assuming most people will end up going at least 51 demo or 51 affliction before going destro, that the current 21 pointer in destro could stand to be changed to help destro warlocks where they need it most right now: PvP viability.
So my idea is to basically get rid of the 5% crit talent, melt that lost DPS elsewhere into the tree, and replace it with something that would actually change a warlocks playstyle.
You wanted to give warlocks a different type of CC and make them less reliant on fear. That was the whole idea for introducing cripple, was it not? Well, why not give destro warlocks a chance at squeezing some sort of new CC in that would solve some of their issues (mobility and survivability), but NOT reintroduce cripple.
The first thing that came to mind was aflame wreath type ability, similar to the Shade of Aran in Karazhan, even if only a single target version with a moderate (30s or so) cooldown. Think chains of ice that locks you into place for a short duration via chains of fire, preventing movement for 2 seconds, but allows you to move after that, at your own risk: Any target who attempts to move out of the wreath explodes, dealing damage to all around them, and also burns away Y resources (lose a bit of rage/energy/RP/mana). I think that could be pretty cool.
To make up for the loss of 5% crit via devastation, you can simply melt that into the tree elsewhere.
The only other thing I was thinking of, was introducing a new "armor" for locks, to match more of a destro play-style.
Mages have Molten armor for fire specs, frost armor for frost, and mage armor for arcane (although the other armors can still be useful for arcane, too).
Warlocks basically have a PVE armor and a PvP armor... And to be honest: I really don't like demon armor at all unless I know I'll be catching a ton of heals. The 2% health regen and extra spell power is clearly superior for double DPS 2s, triple DPS 3s, and any small scale combat when you're not being followed/spam healed by a pocket healer, and/or being focused. When I do BGs, I almost always prefer fel armor.
I really think Demon armor could use a little boost, either with the physical damage duration reductions, or something along those lines. I at least think Demon armor needs to have it's flat armor increase # scale with another stat, such as spell power.