Instructing people or convincing them the game isn't lost because they can't stomp is impossible. I don't have the patience for that. I've learned to not care about elo and so far it's been working well, slowly but very well.
There are just so many stupid and stubborn people it's not even worth bothering. Best way to convince them is to simply play and outplay the enemy few times to prove them they are just ****ing bad and need to get their shit straight. That's where you somehow have to go above and beyond the expected skill level when in a player and item disadvantage.