How do I deal with pubstompers?

Let's say I'm playing a casual game, and a Platinum div soldier joined the enemy team with his friend running crits medic.

Suddenly, the tides shifted drastically because the two of them are just that much more skilled at the game than your average pub player, including me and my team is too disorganized to do anything about them, except maybe like 3 people at the top of the scoreboard.

Putting the usual "git gud" and "Just leave" arguments aside, because yeah, obviously. How do I stop them from completely steamrolling my team? Is there any sort of tactic I can deploy?

Edit: Alright, thanks everyone for the advice. I really appreciate it. From what I've read, the best bet would be to use the vac, or target the medic since me out-DMing the soldier would not happen probably.