IMO random teams creates more problems than it solves.
If you absolutely want to do teams and absolutely want it to be 4v4 then have people sign up in pairs and then group pairs together into a team of 4. This way they can practice and be effective with their friends and it can still be balanced by mixing the pairs you know will be really good with the pairs that aren’t.
I think if you take away the friend aspect of this you’re going to lose players. People want to play with their friends and being tossed onto a team with 3 people you’ve never seen before is a major turn off. Unless they’re all good, then it’s a major win.
I don’t play XBOX or non-PC Halo but the Team Fortress 2 and Left4Dead tournaments are the exact same way and finding a consistent way to create balanced teams that contain people that know each other has taken many LANs to perfect. We have a way now that works pretty *edited* good but I don’t think it would apply to consoles as well.