Well we need to consider why Zenyatta was nerfed in the first place. The "God Comp" of 2 Zenyattas, 2 Genjis, 2 Symettras, where Zenyatta's old "fire and forget" orb was used to buff the two Genjis into the stratosphere in higher levels of play. Having two health pool buffed, healing Genjis in your back line constantly coordinating and covering for each other made that team composition nearly mandatory for a long while in higher level play. So they made it impossible for Zenyatta's orbs to super buff those flanking characters by making the effect LoS leashed. And this works, the God Comp is no longer used in higher level play (Hi 2 Tracers, 2 Lucios, 2 tanks, you fucks will suffer as Zenyatta players have suffered...), however, it's gone a little bit too far and has served to highlight the flaw in Zenyatta. Without being able to exploit his orbs for flankers like that he doesn't really have a solid role in the game. Sure he deals pretty decent damage (I think his charge shot could do with charging a little faster) and Discord is somewhat useful but he's way too squishy for what his abilities and his speed should allow for. He can't rewind time like Tracer to heal himself, he can't wallrun away or jetpack out of bad situations or anything like that. He's just way too squishy with no way of actively getting out of those situations where his low HP pool suffers and so in higher level play he will just be picked off by any competent Tracer, or Genji, or Mcree, or Reaper, or Widowmaker, or anyone who can go "Oh look a low HP healer who's moving slowly in a predictable way? Must be Christmas!"
So there's my issue for Zenyatta, survivability. Make him a close in DPS-Support if you want to keep his orbs LoS leashed, but he needs to be able to live longer than 3s with his team in order to be useful. And no, his ult giving him temporary invulnerability doesn't count because people shouldn't have to rely on their ults to get them out of this kind of situation when most other characters have advanced mobility options.
