I was not aware that picks affected the elo gain and loss, where did you hear/see/read that?
I think it may be a good idea if the Matchmaker also looked at how many times a player was banned in the past 1-2 month period, and lessen the ELO loss a team receives due to the system assuming this player will continue bad behavior (and negatively affect the game). Or even place a player who's ELO may be high in a lower ELO bracket (Ranked or Normal) due to constant bans/suspensions/reports of bad behavior.
The Matchmaking system and the Tribunal should be a co-operative system, not a separate one. The Matchmaker SHOULD take into account a player's Tribunal history, and I think the Tribunal should get a player's matchmaking history (e.g. see if they have been going down-and-down the ELO ladder with consistent ELO losses, negative K/D, things of that nature, even if the Matchmaker assumed that player's team would win.)