I only play support right now and I can say that there is multiple way to get rid of nasty flankers.
Lucio just speed and boop them all around, Moira insta lock and zone them, Brig pressure them bad, ana can sleep/nade them, Kiriko and Mercy have so many tools to run away, Bap and Zen I find the harder, but if you lucky or really good with Zen you can kick them around.
There is ton of tools, and if the ennemy team have two divers, it make two people less on the ennemy front line, where you should go support instead. Stay between you tanks and your dps so you can heal the tanks and the dps will have no choice to help you.
If you have a diver team go full diver support. No point in staying behind with Ana you will be meat.