Well, when Showdown was going on, it was:
- First Blood
- First to take down a Tower
- First to reach 100 CS
For duoQ, it was first to reach 2 kills.
In that match up, unless the Blitz was VERY ahead, Yasuo would have had a much greater chance of winning simply because if he was able to kill Blitz or make him back off, he could clear a tower/inhib/nexus faster than the robot.
When my friends and I fight each other, it's almost never to the Nexus, unless it's quite close (only happened once, and that's cause there were disconnects). Heck, a lot of the time we actually ban the attacking of towers simply because AD champs would win unfairly in that regard (though once the outer towers go down, that's lifted, agreed upon before the game starts).