Overwatch‘s Principal Designer, Geoff Goodman, has said that Blizzard is looking into nerfing Zenyatta in an upcoming patch and is considering some tweaks for Mei and Mercy. Responding to several posts on Battle.net, he said explained the changes as follows:

Zenyatta:
Zenyatta is definitely playing a lot better these days. At this point anecdotal feedback, internal stats, and competitive feedback are all showing he’s actually a bit *too* strong at the moment. At this point we’re looking likely to reduce some of his power in an upcoming patch, probably related to his Discord Orb.

Mei:
While Mei currently doesn’t see a ton of tournament or competitive play, I don’t think shes super far off. Currently her ult can feel a bit unwieldy and inconsistent, especially when you compare it to other similar ults such as Reinhardt’s. We’re internally testing allowing the ultimate projectile she throws to pierce barriers (such as Reinhardt’s shield), and increasing the radius a bit on it.
As for Mercy, Blizzard has been trying out several changes, some of which haven’t worked. The developer is still considering different tweaks and said that if she were to get a new ability, it would “ideally have to be something that she could use more ‘outside of combat’ or something that is generally used much more rarely.”
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