I'm sorry to say it OP, but nobody wants to sign up for your "leagues" because you made 5 basketball "league" topics. None of them were successful, so what does it matter?
Boxing exists in real life. It's an actual sport. It doesn't mean he would be "stealing" it if he made a league, would it? No.
You can't just create something and expect someone not to take your idea. Same goes for the invention business- even though something is patented, there are rip-offs of a product. That's the issue here. It's perfectly fine.
If you think you can make a better boxing "league", be my guest, but you already made 5 basketball topics and are continuing with sports topics, without reaching success in the least bit.
Also, it is not okay to open a topic and not accept negative feedback. This is the internet, or for that matter, this is LIFE, and people aren't always going to be on your side.
Ravencroft didn't even copy you entirely; he made a 1v1 TOURNAMENT, you made a boxing LEAGUE. There's a HUMONGOUS significant difference there. You could have signed up for his tournament, but it's too late now.