To be fair there's very little difference between Bruisers and Tanks atm with current season 3 itemization and masteries. They all have damage output that can't be ignored and they all take pineappleing forever to kill.
Probably one of the best things about the upcoming mastery sets is that it will make the difference much more obvious.
As for Yasuo, IMO his lore screams assassin with a samurai motive.