Solo/duo system seems so broken and lost.
Why is League, this great team sport with its well-planned and functional MMR system, trying to make players be responsible for other players they don't know from Adam?
In 5x5 and 3x3 matches, League of Legends comes into it's own with teams, strategies & synergy. Your team's victories and losses are all about what you and your team accomplished in your scheming and designs. This is positive reinforcement.
In solo/duo queue, you are rewarded and penalized based on your team's victories/losses. Except that these aren't your buddies. You have almost no rapport with them nor level of relationship where you have an idea of what they're doing. You don't have any idea of their capabilities and weak areas beyond what you might have gleaned from one of the stat sites while loading up the match. This forces players into the many infamous situations that we always see complaints about: "Le Blanc open!", "First time Mundo!", "Jungle or feed", "Stop feeding Draven, Soraka!", "I'm not a good Top laner", the list goes on and on. I'm not sure what the goal of this is, because unless you're really good and can carry all your teams comps all the time, you're not going to get much pleasure out of the matches.
IMHO, solo/duo queues should either be real solo/duo matches (1x1 or 2x2) or the reward system needs to be altered. I'll give props for endeavoring to get random people to play together as a cohesive unit, but that is not feasible in reality without a few warm up laps at least.
One thing that might help is implementing the team builder for ranked.
Hope to see some constructive information here.