Both Mercy’s skill floor and skill ceiling are pretty damn low. She either dominates every rank or becomes a bad pick once you get into slightly high ranks. Mercy 1.0 was great in 90% of the ranks, but became pretty mediocre in the top ranks. Mercy 2.0 was too strong in all ranks. Mercy 2.5 is now too weak in many ranks. The devs will probably buff her to 55 hps or something, but Mercy 1.0 and 2.0 weren’t much better than Mercy 2.5… just worse in different ways.
Fitzy/Danteh thought it would be a straight nerf. From their explanations, it was clear that they expected her to remain a purple Tracer that can hack things. Now the meta shifted and Sombra’s playstyle compliments it well.
I doubt many buffs will cause Reaper or Torb to define a Meta. But it’s certainly possible with Symmetra. Overbuff left-click and now she’s a 100% charged Zarya, overbuff right-click and she has pseudo-Pharah rockets, overbuff teleporter and she has the strongest mobility tool in the entire game. Imagine how crazy teleporter would be if they removed the 2 second deployment time. What if they changed the charge time to 1 second? They’re taking it slow with Symmetra, and I think that’s a good thing.