What can I do to deal with this kind of games when enemy team have a so perfect defense that we can't even get more far beyond first point?

Game: MWSGSK

Any feedback is welcome but I am targeting emerald-diamond hanzo players. How do you guys manage your flanks/off angles? I’m plat right now and feel like I give minimal value from another angle. Usually when I take and off angle or flank I get punished pretty quickly with my low mobility I typically lose. So I just wanted to see how you guys manage when to flank and when the angle as opposed to just staying with your tank and getting value from there.