Please put a ready check in game.
There is sometimes a long loading time before matches. During this time players will afk or alt-tab, and miss part of the beginning of a match. Alternately, some people don't connect or the game hangs on the loading screen. A ready check in game would easily solve the problem of afk's and dc's because of problems during loading. This is a common feature of other competitive games, I don't see why not in League.