Winston is in a weird spot because I think he's basically unplayable at lower echelons of play. Like, if you're in Bronze you basically can't play him at all. There's too much enemy DPS, not enough healing on your team, no coordination on your team. Once you get to Gold he's sort of playable, especially if you can get a small crew together. My team was getting crushed on Numbani attack and I went Winston and I told our D.Va main "Call out who want to attack and we'll go in together." And that small change became very powerful, Winston and D.Va attacking together just seemed to cripple our opponents who moments earlier were handing us our hats.
At even higher ranks I can see how he merely gets better. The game is faster there and Winston is the fastest Tank so it makes sense that he's strong at these absurd ranks.