I have had multiple 40+ elimination games with Winston now. I haven't recorded anything, but I'm really comfortable playing him.
If you have tried him and it doesn't seem to click, try playing him like Lucio. Be at the edge of the point, moving around, using line of sight to block enemies. Keep things contested. Jump to disengage or close the gap on a damaged target. Never, ever, jump to engage.
Another HUGE pro tip is to remember that you can start his leap while in the air. So jump off the top of something and get people to follow and while in mid air, leap back up. Or pretend to fall off the edge to lose aggro and come roaring back. Greece is the best place for that last tip.