Have not played SP in this season. But had a wonderful and fun exp in a4 as a SP, and then as Dis. Both specs are fun and have a lot of similar in tactics.
Actually all i see is a buff of SP - 51 shadow tree talent and 100% bonus crit/high crit rating on gear. There was and still is only 3 class that can do insane burst damage in pvp: Arc Mage, Multi rogue and SP. No other class can make something like that in a very short period of time.
Yes there was and still is a problem of choosing partner - only rogue will suit.
As for a4 season - the only problem for SP/rogue combo was 2dd combo with a rogue. Just because priest could not survive or escape the insane start burst of such team - that was changed by giving SH 51 Stalent. It will give your partner much needed time for creating you a save_time passage to prepare an attack. And you will keep most of your life. Just use it like a frostmage its iceblock - not when you are low on HP but when you or your partner don't have CD to run/let you run away.
As for h/dd: if you start and keep pressure - you'll win most of the times. If not - your skill will be shown in such battle. Lost game actually
.
As for CC - SP has a plenty of it. Fear for trinket the enemy. Silence when you partner is ready for finishing burst and the burst target does not have trinket.
Actually - even if silence would have a 10 min cd that would not change much. It is a one use spell. Mostly :P
2dd combo is a very hard to master - one mistake and the battle is lost. Not lucky - resists and the battle is lost. That's why blizz tried to make the game less casual by removing stun chances and so on...
So i don't think SP need any changes. It is hard now. It was hard last season and it still is. Just get resi. Lots of it.