Suggestion, re: dodging
So, it sucks being stuck in a game you're 90% sure is going to be a loss due to either people trolling in lobby (before game even starts) or picks that you think are awful. Oftentimes people either straight dodge these or try to get other people to dodge. How about adding this feature: "No confidence" Button. In the game lobby, you can click this button. Once the game starts you play as normal but at the end if you selected "No confidence" then all LP results are cut in half. (so half gain on win, half loss on lose)
Along with providing (hopefully) a better experience for players, it should provide an obvious data point for developers both in terms of the success of matchmaking, but also on people that consistently are seen as "liabilities". If someone is ALWAYS in a "no confidence" game, then that should be a red flag about that person. I would even suggest if ALL 5 players on a team vote "no confidence" then nuke it and get new lobby, but that's optional if concerned about abuse. Another option is something like reverse autofill ie. if you go "no confidence" for X games in a row, then it is disabled for the next game.