There's a new balance patch out for Overwatch today, coming just a week after an earlier patch introduced new character Ana and gave a significant buff to McCree.
Those two characters are also the focal point of this week's patch. Ana is getting a slight buff, as her rate of fire is increased along with the magazine size for her primary gun.
McCree, on the other hand, is getting a nerf. It turns out that last week's buff - which increased the range at which his gun dealt maximum damage - was a bit too powerful in the hands of top players, so Blizzard is dialing it down a notch. The range at which damage falloff kicks in is decreased, meaning McCree will be less effective at longer distances. But despite the nerf, he's still more effective at range than he was when the game launched.
Stop by the Overwatch forums for the full rundown.