could mix with tourneys, but not with leagues IMO.
Dunno how you wanna award 'league'-like points to cups though. You can implement ELO there, which would be pretty fun IMO, but well... there's so many different schemes in cup.. you would need tons of ratings then.. or limit the choice in schemes

Or display/count only the official TUS schemes and ignore the rest.
It also seems unfair to proceed the player with the lower rating. I'd rather have the guy with the higher rating proceed... seems better for the tourney and more 'fair'.
Current rankings are kinda ok. People don't really notice them though.. and if they do, it's kinda most active players >>>>> rest. Chelsea is a great wormer, but he's only on top cause he plays so many cups. And same for me in 2nd place. But I really don't know how you can avoid that.
Maybe a hall of fame for cups would be nice, where lists are available for every scheme. So you got a list of winners in elite cups. That's kinda cool