"Hero" mode: Mitigating game losses due to leavers.
Direct statement: A system which allows other players to take over the role of leavers from games in progress.
Although the League of Legends "LeaverBuster" system is designed to discourage players from abandoning a match, intentional leaving still happens far too many times - resulting in a loss.
Let's say someone has expressed frustration and/or intent of leaving, then disconnects, afk, or is inactive. After some duration of time, such as the LeaverBuster's 5-minute mark, the remaining team can initiate a vote - similar to /surrender, maybe "/callhero" - which may remove the ability of the player's return, while opening up the position for another summoner. The team always retains the option to not initiate the call for a hero, with a 5-minute time limit between vote attempts.
Upon a successful team vote - which could be displayed as "Call for a Hero?" - the disputed position/champion is now open for other players who own that champion to take over in a "Hero" mode - similar to spectator mode of the random matches listed on the League of Legends home screen - potentially saving the remainder of the match for all the players which did not leave.
Incentive for the "hero": since the team with the afk has been spent at least 5-minutes without a (poor quality) teammate, they are disadvantaged and more likely to lose. Thus, the hero should lose a reduced number of the normal League Points (for ranked) or an IP bonus (for normal) for a loss, as a way to say thank you for trying.
In order to prevent serial heroes with lowered risk, there should be a season annual maximum rank contribution from hero matches. Such as, win x number of hero matches to get a rank level increase, limited to x rank increases per season.
There could be a system which preferences summoner's with the least number of hero matches - so that no one summoner gets an unbalanced advantageous lead in ranking.
Additionally, the hero queue should also be subject to the new dynamic ranked games system, so that a platinum player doesn't play hero in a bronze match.
Implementing this mode would drastically improve the ranked experience, which is when this frustration of losing due to a leaver is the greatest. The punishments for leaving should be the same. This system will mitigate the losses due to leavers and reduce the amount of ranked points removed due to another summoner's poor behavior.
The result should be improving player's experience overall, raising the quality of player environment for new incoming summoners, and better keeping to the League of Legends summoner's code.