As per another thread in PvP forum, let's have a Championship bracket to split all tiers into casual and expert.

Get 25 wins in t2
Get 25 more in T3
Get 50 more in T4 to be bumped into an experts level bracket. EXP can be frozen but only in the expert level. Once there, you can't leave unless you get double the losses, and if you leave then you can't go back for a certain amount of time.