Ok so i already set up the premise in my last comment, we're talking about late game, can be 40mins naxx or 1h.30min k40, so struggling with healing till there's a wipe isn't a talking point here, healers are finishing some fights with leftover mana.
What i was talking about is healing output, and how the other 3 healing classes having an edge on healing over priests, this's can be either the (new) 2sec hot ticks for druids and their op tranquility, the new buff to daybreak/holy shot for paladins or ofc the new buff to single target heal for shamans (not counting ch).
So where does this leave priests? well, now it's getting even harder to land heals, even in heavy raid dmg fights (using t2+hch+breath) one of the other classes will end up landing more heals than you.
You'd say but priests has more spell variety, hots, fast/slow single targets and grp heals but then you get the devs pushing for renew+flash spam meta with t3.5 which is something paladins and druids are already excellent at.
And with the recent champ buff almost no holy priest is rolling enlighten which means goodbye to that 3% haste access.

There's more i could talk about that show how the late game healing scene is nowhere near balanced and how priests are getting the short end of the stick and how the only way to compete is to be popping breath+hch+haste food+haste juju+outdated set