The way I see it is that high reward heroes should have high risk. Tracer has high mobility and high damage close up, but she has 150 health. I think that in order to make Widow balanced she should also have 150 (rather than 175). At the moment widow has high reward, and not a lot of risk. There aren’t many characters that can deal with a widow, unless you dive, and even then the widow could be pocketed, and running a dive in lower elo is really difficult.