My last 6 ranked games have been a mix of people going afk or disconnecting/reconnecting because of high ping. This is not caused by Riot's servers since my ping was 36.
There is an easy implemented solution to this problem. While searching for a ranked game, calculate mean ping against the servers, if this is above a certain unlayable threshold then do not allow a ranked game - instead show a graph of ping over time and suggest solutions. Often problems can be fixed by restarting a router etc but in some cases it's about infrastructure or temporary errors caused by the ISP.
As a player i would appriciate this information since it is really causing problems with the game as it is.