You got lucky as sin then hehe. My LFR This week
1st wing 1 wipe on Sha of pride.
2nd wing 2 wipes on Galakron, 5 wipes on Dark Shaman and 4 wipes on Naz
3rd Wing (came in on second boss initially) 7 wipes on Spoils 5 wipes on Thok (reque for first boss) no wipes.
11 bosses 24 wipes (still not bad for lfr) all but 1 wipe on spoils was due to 3 lvl 496 tanks who didn't know the fight.
Flex this week.
1st wing no wiped
second wing 1 wipe on Dark shaman
third wing 1 wipe on spoils (the nerf took us off gaurd) and 1 wipe on Thok
11 bosses 3 wipes.
Both lfr and flex was done on the same toon also.
But to the OP. Yes flex hurt LFR because good players no longer need to do it to have an off chance at gear from their normal/heroic raids, but it is mostly due to it being new content and just bad players in general. My 58 year old mother is usually in the top 5 dps and almost always lives to the end of a wipe. (140k ish dps from her)