New clubs (finals)

Players who have no business being in the Pro Cup playoffs is certainly a problem.   Unfortunately, I don't know if there's a good solution.  At least not a solution that wouldn't be easily bypassed by the types of players who want to run smurf accounts for the playoffs.

Flat out banning new clubs won't work.   People will just create a new club in advance.   Plus you don't really want actually new players to be locked out of the mode they want to play for up to a week and a half because they just picked up the game.

Requiring clubs to have played a certain number of games runs into the same problem with actual new players ( or even just casual players ).

Limiting how high a players RP is won't work either as people will just quit-lose games on their smurf accounts until they're low enough.

You could run the playoffs only for the Elite tier ( probably just make it for division 1 teams only ) and run normal club matches for everyone else in parallel.  That solves the smurfing issue, but takes away the fun of the playoffs for lower tier clubs. Of course I'm not sure how much fun they're having getting crushed by teams that shouldn't be there as it is now.

Or maybe just run playoffs and normal club games at the same time and let people choose which to  play, but that doesn't really solve the problem, just allows people to skip it.  

Even reverting back to the old four-and-out playoff system is problematic.  The last couple of years that system was in place so few people were participating my club found it literally impossible to find games.  Even on the first night or two of the playoffs.  It go to the point where we just stopped participating entirely.

I'm honestly not sure you can have a playoff game mode that is both competitive and inclusive to all players.