Mustafa Christmas.
These two words mystify unranked players across North America. He disconnects at the CSS, even if you’ve never played him. He disconnects after one game. If you’re lucky and don’t offend him, he’ll play a full set - although no one knows how to do this. No one knows who he is what he wants, other than to disconnect. It doesn’t matter how many times you queue into Mustafa Christmas at four in the morning, when you’re very obviously the only two people playing in your region. He’ll disconnect however many times it takes for you to find any other player to fight.
In all seriousness, there are a decent amount of chronic disconnectors in unranked. What prompted me to make this post is a player named Pîxêl, with a 98 win-streak in unranked. I’ve encountered Plup, Animal, and a few other top players in unranked before, so I didn’t think too much of it until I got in-game and took the first stock, at which point they disconnected. In other words, they were disconnecting the second that their win-streak was at risk, and did so all the way to 98. (Other players confirmed that disconnecting doesn’t reset your win-streak in unranked.)
We all ALT+F4 every once in a while, but there needs to be some system in place to penalize players who do it repeatedly, of which there are not an insubstantial amount of in unranked. This is all the more necessary because blocking players on Steam does not prevent you from matching with them (which I’m fine with).

If only there was a block feature we could simply block players who do that so we don’t have to endure this nonsense.