Been experiencing similar server routing issues.
Performing route -f and then ipconfig /flushdns in Window’s command window in admin mode brings pings down from 400 back to a normal 25 on the same server. By that time you’re suspended from the match though when you can connect again and ruined 9 other people’s game.
Means Overwatch is doing something silly with their dynamic server allocations.
Doesn’t happen in literally any other game.