Your placement matches also take into account your personal skill level - if you're preforming well above average, despite your win/loss, you will rank much higher than others (minus the current KotH shenanigans).
For reference, most of the top pro players were initially placed at 65 to 70.
I would like to see Reaper nerfed across the board. In fact, I'd LOVE if they just removed him from the game completely, but that obviously isn't going to happen. I can't think of any way to change his existing skills without just making him boring to play. Playing as him IS fun, but playing against him is the absolutely fucking worst. And it's pretty much guaranteed that someone will pick him in every single game. Fuck Reaper.
Also, I've been playing more as Roadhog recently and realized that his Ult really, really needs a damage boost. I've had it focused into crowds of players and at single players at close range and not had a single one of them die, sometimes dying myself immediately after it's over. Something's wrong there.
A full Whole Hog does 2500 damage, this is just a case of not aiming it well.