The fact that nobody went to games doesn't change the fact that the ABA was filled with professional players, many of whom were hall of famers. Dr. Jay didn't dominate a bunch of bums. He played in a league that had players like Moses Malone, Connie Hawkins, Artis Gilmore, George Gervin, Rick Barry, David Thompson, Mel Daniels and more. A lot of these players went on to dominate in the NBA in the NBA as well.
So it's not like these ABA players were excelling in the ABA and then went to the NBA and stunk it up. The ABA didn't succeed due to many factors, the main being the lack of TV contract, however, the ABA was created with the intention in mind of forcing a merger with the NBA and it worked, for the most part.