I've made a lot of interface improvements on this. Meanwhile, that's helped me discover some obvious tier promotion issues that I'd like to address before I show you the new code.

I'm also thinking with the relative bottom tier and auto-promotion, there can be a lazy version (force people to continue to go through the lower tiers when vacancies occur in higher tiers) and a greedy version (let the lower tier matches continue, but make sure to populate every higher tier with any queued players). Heck, someone could also make a "smart" version, so I might rewrite the code so people can more easily experiment with that.