You should never have a player you reported in a previous game, on your team again
Im not really sure what system riot has in place to handle reports and making teams, but honestly this seems like it should be a no brainer.
If I report someone for something, I shouldn't have to worry about having them on my team again, let alone in the very next game.
I just got out of a game in which my teams support Alistair, after losing a single fight in bot lane, got in a temper tantrum with our adc Twitch, and decided he was going to afk and eventually troll for the rest of the game.
Naturally, after the match ends, I report Ali for Unsportsmanlike behavior, verbal abuse AND leaving game/afk. Not one but THREE justified reports from me against this player, and then I move on and queue for another match.
And what happens? This player is placed on my team IN THE VERY NEXT GAME! I decided to warn the other 3 players that this person is toxic and a troll, and then proceed to dodge the game, because I have no interest in spending another 20-40 minutes with this player, and now im the one that gets punished. Now im the one that has to sit here twiddling my thumbs waiting to get to queue for another match, because this current system has this serious flaw in it.
Riot, please fix this. I should NEVER have to deal with a known toxic player, that I have reported in a prior game, on my team again.