Pick your poison but one of these statements is true.
At the top tier of play Mercy is outputting less healing than Ana while also dealing next to no damage and getting basically zero eliminations.
If we look at the utility each hero provides, Mercy brings resurrect to a fight but Ana brings both her nade and sleep-dart.
Nade on its own has comparable strength to resurrect and sleep-dart is probably the strongest CC in the game, considering if you can hit it.
Furthermore, Ana’s ult is a lot more impactful than Mercy’s ult, giving Ana the edge here too.
Mercy does have a lot more mobility than Ana, which should help her survivability but looking at the stats, at GM Mercy dies an average of 6.96 times per game, while Ana dies an average of 7.5.
For the lack of mobility Ana has, her survivability in a game is still pretty frickin high.
Finally Ana’s pick-rate at GM is 11.95%!!!
I have to state just how insane that is!!!
That is initial rework Mercy lvl’s of insanity, she is basically making the meta at this point and I can say that because Ana has in fact had the highest pick-rate in the entire game for over a year now!
Mercy’s pick-rate is 5.05% if you were wondering.
In conclusion, either Mercy needs a buff to be able to compete with Ana or Ana needs a nerf to be brang in-line with the rest of the supports.