I propose that whenever a character is reworked, not just tweaked a little, there should be an accompanying storyline which explains or at least references the change to the character in terms that make sense within the OW universe.
Over time, this will build up an archive of lore that is naturally connected to the game and explains character changes in terms of their story arc.
Another example of how this methodology could be applied is by creating a story arc that is based on the changing meta, so as the game moved from a dive meta being dominant to snipers being dominant the writers can cover this change in the form of a story within which the change is explained in terms of the motivations of the characters and the goings on of the universe in which they exist.
If we make the lore tell the real story of Overwatch, I believe it will be much richer and a much more valuable asset to the game.
So… as an example… let’s take Hanzo’s scatter arrow. Why, within the universe, might he have switched his ability? Maybe one day he fired a scatter arrow and a ricochet hit someone he cared about that was coming round a corner… and so he decided it wasn’t safe to use. Maybe his arrows came from a specific factory that was infiltrated and shut down.
There are multiple ways you could explain the change that are consistent with universe and enrich the development process for users.