Personally, I HATE tournaments here. A: the bot armies, B: the whales who run a dozen+ accounts and mass-populate each tourney, C: the oddest of schedules and time blocks for each one.... w.. t...h??? Sure someone on the globe is awake at that freakishly odd hour for that... but not me! haha And then D: watching the Champions absolutely shred everything in the Novice league.
Ever raise fish? Ya... big fish EAT the littler ones. WHY!!!!!??? Why would you deliberately put the small players in the same pool as the big ones and think they had even the slightest of chances? Horribly macabre amusement???
I like your idea of choosing a league to pursue. But take it one step further. Lock tournaments to specific card levels: Bronze uses level 1 cards. Everyone in Bronze is locked to that level cap. Regardless of weather your gold foil Julian is capped out at max. Silver is level 2-3, Gold 4-5, Diamond and champ etc, etc....
If you don't meet the minimum card level, you can not play or pursue that league. Want to get into the next league? Level up your cards and jump in! But if you want to pursue a lower league, you do so knowing your cards are going to be capped at the appropriate league bracket.