Generally used in chess to denote a clumsy or novice player, Patzer; from the German patzen which means bungler also describes anyone of low abilities trying to perform beyond their capabilities. In other words, trying to play or perform above their class. i.e. out of their league.
Usage: "...did you see that schmucky guy trying to chat up that beautiful woman...? Yeah, he's a real patzer! He'll never score with a beauty like her. She's way out of his league..."