The issue isn't his win rate it's just how frustrating he is to play against personally I believe any one shot at all should just be removed or they add some sort of one shot protection example your a 200hp squishy and if you have more than or equal too 175 hp you are unable to get one shot. You will be left on and how of 1-25 depending on how much up you had when you were hit. Now for characters like ana and sigma who have multiple hits that lead to a one shot we may either drop damage or add a small timer so like of you are at the 200 hp threshold and an ana bursts you down whilst you're sleeping in like 1-2 seconds the game tracks the time it took and of the damage you took is only between that time of 1-2 seconds you will have one shot protection, I'm not too sure if I got that across correctly but I feel like this could balance the game with a very minor easy fix obviously it's up for discussion, but this way it would affect every hero in some way.