TBH that's your fault for not shutting down an assassin early. Yasuo does especially bad after level 3 and before he gets his shiv, so if you don't hit him when he's weakest, and only when he's fed off your teammates, I don't know what to tell you. His damage and lifesteal core item is what you need to look out for, and that's the thing that also is holding him back from being more than just a feast or famine assassin.
Most Yasuo players that start feeding will not be able to stop, and you will likely see them crying in the lobby about your champion after his team could not carry his weight. It happens all the time in bronze/silver. All the time.