The Lakers, Mavs, Heat, Knicks, Magic, Bulls, and Celtics are always good and attract all the top free agents?
What free agents has Boston ever brought in, especially during the roughly 15 years of losing between the Big Three's?
The Bulls were a great franchise exactly once, and it had a little to do with a guy named Jordan.
The Magic I don't recall bringing in any good free agent, and have never won a championship.
The Knicks have been an embarrassment to New York and the NBA for the last decade.
The Mavs won this year after years of failure. Cuban overpays for everyone.
The Heat were decent (and ringless) in the 90's. Wade fell to them and they got a superstar in Shaq who demanded a trade. Then "the decision" happened. Before that, no free agents really cared about the tax break or the hot weather.
I'll give the Fakers credit, they always seem to stay respectable one way or another.
Great players usually get drafted by the bad teams, which are generally from smaller markets. They simply need to do a better job of keeping them happy. It has less to do with location (I'm sure 'Melo loved the city of Denver and DWill loved Salt Lake City) and more to do with the lack of confidence in management to get the right mix of help.