IF YOU CANT WIN GAMES BEFORE GOING OOM YOUR DOING IT WRONG.
The EU people namely Lolflay and Calx, have made good points about satin.
I'm just trying to present an alternate take on it. Of course the argument can go both ways, but the points the crit "school of thought" make really only work against bad teams or teams you'd beat anyways (without crit or without mana issues).
If both stats do very little for you, it seems like the "optimal" way to go is to pick up the stat that isn't RNG and is working 100% of the time instead of 10-20% of the time. I still stand by point that you should be able to beat every single team without crit, but there are teams you absolutely won't beat if you go oom...so you can try and play better and not go oom, and have your crit not get you any wins, or you can just bite the bullet and accept that having mana gear would make those particular games that much easier. Examples where offhealing and dispels and dot uptime and mana save you: shadowmourne dispel cleaves, double shadowmourne TSG, beast cleaves, other wizard cleaves, etc. Those are extreme cases but it also obviously works vs. standard comps allowing you to recover from a bad situation. Mana helps you in all undertakings even in quick games.
On a top BG against top players, the subset of games where crit is 'doing more for you', is smaller than the subset of games where mana is 'doing more for you'. I'm not advocating full mooncloth 100% of the time, but definitely some sort of regen such as 2pc+meditation or a solace or heck even mana efficiency in your build. It helps a ton and really creates more momentum then "using your cooldowns properly"...when you can dispersion against a PHD for a fear or pop fiend for extra damage and know you don't need any mana back from it, or not have to go and drink and reset the fight because you still have mana --> then you're doing more pressure than a few RNG crits and that to me is playing the spec correctly.