Sometimes, you just can't help but get frustrated while playing a game. It's fair; we're human. But it's probably in your benefit to keep cool and not rage while playing -- at least, if the game is League of Legends.
Riot, the developer, has collected evidence to prove not just that ragers lose more games, but that people who use teamwork win more games. Looks like "teamwork is OP" isn't just some meme! But hopefully that's obvious, right?