I play in a group of friends who are usually a 6 stack, and we don't even know who the problem person is / are. We just know that we always get in the 'wide range' match making and as soon as one person calls it a night we can't queue with 5 so we have to kick someone out. It sucks.
This is a design decision Valve has made, and it absolutely sucks. I play with a large group of friends, and we're often a 6 stack. But it means as soon as one person calls it a night you have to wait to either get someone to replace them or argue about who is going to drop off with them.
