Oh god
Ret Rsham is the only, ONLY viable comp for ret in 2.4.3.
It will get better in s4. Why? Firstly because Shaman becomes even more immortal, same with ret, you will manage to survive more melee, not counting any caster comps because they ain't problem for this comp at all if you play correctly (and those who beat u in S1 will beat u in S4 anyway). Shaman will tank any warrior and rogue without any problems. And if you play well you can reset and prolong much easier.
Why this doesn't hurt you is because you wait for your big crits and procs anyway and if they happen you win, so the later season only helps you survive long enough to have more and more chances each arena to get those procs and retreat, drink, reset and wait for CDs if you fail, that's how you play this comp.
I am not talking about ret shaman that just goes oom and when ret gets burned once it's game, games take really long especially because you need the RNG to actually kill something, you need to resist kidney here and there, then get two WFs in a row, possibly resist MD on bubble, but you must be capable of giving yourself as many chances for this to happen as possible with constant resets.
On the other hand this comp is very forgiving on mistakes especially because you can just turtle if you make one (obv not vs RM and such).
And along with S4 comes Vial that both of you can play if you want to play gay even more.
Good luck