(Name removed because it's not allowed to name and shame and stuff)
The guy is obviously not Silver 5. He just enjoys stomping people at low elo, then lose a bunch of games on purpose so he doesn't move up the ranked ladder.
He just avoids dying too much because the automated system doesn't think you are intentionally feeding if you don't die over 20 times in less 15 minutes.
He also DuoQ's with another guy who does the same thing to make sure they don't move up the ladder.
If a 4v6 is barely winnable, imagine a 3v7, especially in low elo.