True, but a few of us definitely seemed to be pulling enough weight to compensate for one dude who is terrible. And that's supposed to be part of the whole idea of flex, that one shitty dude doesn't necessarily bring down the whole raid.
Hard to really discuss it further without dps meters, sadly. Otherwise we just have our opinions.
Maybe you guys didn't cycle the appropriate DPS through the other-realm?
If anything I find Flex to be ridiculously easy. LFR is tuned weirdly, though - Sha of Pride doesn't even have the tank swap mechanic, for one. Norushen has auto-other realm, etc. But Fallen Protectors still have their rez, Dark Shaman is stupidly hard, so is Nazgrim... It's just... weird.
I was actually annoyed there was no tank swap mechanic for Pride in LFR, but part of me thinks it's because they assumed the rest of the raid wouldn't handle the adds properly so they wanted the other tank to do that part.
And even though we one shot it in my LFR last night, I saw reason to believe if I hadn't Heroic Leaped over, it could've gotten messy in the raid.