How does the leaver penalty work for Competitive play?

From the Blizzard forums:

• If you leave too many games and your “games played” vs “games completed” percentage falls below our required threshold, you will receive a warning message (this percentage is calculated based on your 20 most recent games).

• If you continue to leave games after receiving a warning (which will display in the lower left-hand corner of your screen), you will incur a 75% EXP penalty on all future games.

• The penalty isn’t time-based, but instead will be removed once you complete enough games to raise your “games played” vs “games completed” percentage above our required threshold (again, this percentage is calculated based on your 20 most recent games).

• If you disconnect or are removed due to inactivity from a game, it will count the same as if you leave the game intentionally.

• If you leave a game before the “Assemble Your Team” phase is over (i.e. before you enter your starting spawn rooms):

  • It won’t count as a game played
  • You will not be considered a “leaver” in this scenario

• If you leave a game after the match ends (i.e. after you see the VICTORY/DEFEAT screen):

  • It will count as a game played—and if your team won, it will count as a win
  • You will not be considered a “leaver” in this scenario

• If you leave a game after the “Assemble Your Team” phase is over, but before the match ends:

  • It will count as a game played
  • You will be considered a “leaver” in this scenario