When the enemy team tells you to push mid...

do it. It means they are surrendering before 20. Don't go to your lanes and try to fight them or push down the side towers. Just get all 5 of you to go to mid lane and push through for a quick and easy win. They probably have an early afk and just don't want to waste anybody's time. Sure, sometimes a 4v5 can be won. It happens. But it's rare. But it happens. But it's rare.