You have a well established site about football and you are running Yahoo ads on it and even making good money from it. Everything sounds so great. Except one thing, you might get banned before you know.
The problem might be with your keyword. While in the US what we call "soccer", millions of fans worldwide calls it "football". So if you have a site on "American football" (which is known in US simply as 'football') which is optimized for keyword "football" then it might be pulling in lot of international traffic. Many YPN publishers got banned in February for getting non-US traffic and again few weeks back on getting "low quality traffic".
Many banned publishers received mails like this from YPN:
We have terminated your Yahoo! Publisher Network beta account [ACCOUNT ID] for breach of the Terms and Conditions and/or Program Policies. Your breach includes but may not be limited to sending traffic from users located outside the United States, in violation of Section 11(l) of the Terms and Conditions. In accord with Section 6(a), we will not include such amounts in your payment. We have refunded amounts generated from the non-US users to our advertisers and will pay any remaining amount owed to you in accord with the Terms and Conditions.
So in my opinion its best to check the kind of traffic your site is receiving. You can never be too careful.