What are the main problems in Pantheon, why do players drop or leave the matchmaking queue early:
- Connetivity: I hate to say it but some players still can't connect to others sometimes despite proxies. It works for 95% but sometimes it won't work for some reason no matter how long you wait.
- Friend not on the team: Well, you are obviously in the wrong multiplayer mode then. Off you go to Custom!
- Not the right map and game mode: Yes, it's supposed to be random but honestly: I'd rather stick red-hot needles under my fingernails than to play a Fortress match on Crucible (against two tower Rooks, thank you very much).
First let me quote Frogboy who said there should be no or little changes to the UI if possible. For the connectivity and friend issue I'd recommend to use the same lobby as for custom games and remove a few features:
I wish we could get this working without a host but well... So how does it work?
First the connectivity indicator (the green thingy): It doesn't display the ping but it should be green if all connections are established and all pings are below 330 ms. 330ms should work in most cases if the ping is stable. If a connectivity button changes fron green to red and back a few times you know it will most likely lag and the host can kick the player but it will solve all the problems with hosts who don't understand how p2p connectivity works.
Ready button: Yes, the choice of demigods on your team is visible. Frankly, I think it is not a good idea to pick your demigod before you even start the matchmaking. Good luck in your Domination match with 2 Reguli against a team of UBs or something. You should be able to form a team that allows for variety and give you the best possible chance. Why not display the opposing team, too? I think you don't need to know. Every team should try to work out a demigod combination that will work best no matter what is thrown at them.
If the host kicks a player all ready buttons should be set to 'not ready' to make abuse impossible!
Player name field: As you can see it is empty for all players but yourself to make it harder to play with premade teams. I'm sure some people will find a new way to get into the same match and stuff but at least it will help a little. The field can be used by the host to kick players with connection problems or players who can't be arsed to click ready within a reasonable amount of time. It should be only possible to kick a player 30 seconds after he joined the lobby to give players with proxied connections a chance to find a game.
As for maps and game mode, I'd recommend to display both in the lobby. The player should know what he can expect from the game IMHO. It's a game, it's about fun not about ranking - at least not for me. I think the largest group of players want to enjoy their game with little or no regards to 'comparable' rankings. Knowing on which map you will play and which game mode is important IMO. And seeing how many players will rather drop or cancede than to suffer through a game they don't want to play I'm not alone with that opinion. It's better to have a player leave in the lobby than during the loading screen IMO.
AIs: Please give the host the option to kick AIs in the lobby or remove them completely to begin with. I'd rather play a 1v1 than to have a Rook or Torchbearer AI in the game. Both are only good for one thing: to feed the other team.