I think it’s weird how anyone with even a slight semblance of game knowledge could’ve told Blizzard that Mercy’s rework would be as bad as it launched. I remember explaining the rework to my younger brother, and he looked at me, almost wide-eyed, calling it stupidly overpowered and completely broken.
For me, the rework wasn’t that much fun at all; it was so stupidly overpowered, it was actually pretty dull, with the excitement of a successful Mass Rez watered down and spread out over the 20 seconds it originally lasted. Once the novelty wore off, it wasn’t any more fun than simply playing Mercy’s base kit.
So much problems could’ve been avoided if they’d just not forced the e-sports on us, and instead just balanced the game around comp. Replacing the invulnerability with damage resistance would’ve been an easy tweak and addressed a few issues right off the bat, together with the SR fix they released shortly after the rework.
From there, anything could’ve been done, like going back and seeing if maybe that 1 second cast time would actually work now that Mercy had damage resistance. Or add burst healing to Rez and allow it to be used pre-emptively, as well, so the “Mercy waits for her team mates to die” criticism can be put to rest.
The tweakability of Mercy’s pre-rework kit is infinitely larger than post-rework, which doesn’t offer much, at all, as it’ll either be OP or UP. With Valkyrie, there isn’t really a middle ground to be had that appeases both sides.