This is of course a big problem and it happens way to often for my or the opposing team.
I personally feel that there should be some kind of Leave% stat that should be used when making teams in 5v5. Leavers get placed in teams with other leavers. This way you will want to keep your leave% low so that you wont have other people leave on you. The problem right now is that there is no consequence for leaving, the only ones harmed by it are the people actually staying in the game. The leavers should face the consequences of their own actions, in one way or another.
Regarding your suggestions:
- The ready button is a good idea, when the countdown reaches zero and if everyone isn’t ready the team should be given the option to replace the people who aren’t ready yet on their team.
- Kicking players in the middle of the game for being AFK won’t help anyone unless the kicked people can be replaced. If there was some incentive for people to join mid-game and the ability to queue for these games were given to the players this problem could be solved. Helpers could receive double rank/glory, achievements and/or titles for doing this.
- Auto-losing or auto-winning because of leavers wont solve the problem, but it will save a lot of time and perhaps frustration for people and therefore it might be a good temporary measure. I don’t think these wins and losses should count on the leader board stats though.