First of all, Google will get you a fast answer if you want to find out what the NBA team from Boston is.
Second of all, it isn't a factor of how many people follow the sport. Team and league revenues are probably the biggest factor in wages.
Man U had team revenue of $310 million in 2006 according to Forbes. http://www.forbes.com/lists/2007/34/biz_07soccer_Manchester-United_340001.html. The Yankees had revenue of $441 million http://www.forbes.com/lists/2010/33/baseball-valuations-10_New-York-Yankees_334613.html and the sox had revenues of $244 million (now surely higher) http://www.forbes.com/lists/2010/33/baseball-valuations-10_Boston-Red-Sox_330700.html.
Baseball and football have been ruthlessly monetized and, all things considered, salaries aren't that much higher. The average english premiere salary is 1.8 million dollars. MLB's average salary is 3 million. We still have free agency, I don't think the draft has anything to do with it.