A good comparison, I have found, pits an NBA playoff game atmosphere v. an MSL regular season game atmosphere. Switch channels on a rainy Sunday in May between an NBA playoff game on ABC and an MSL game on Fox 1 or ESPN and contrast the contrived, piped-in, thumping "noise" from the NBA arena versus the organic and fan-led enthusiasm from the MSL stadium. I think you'll find that there is no comparison.
At first I didn't understand your inclusion of the Mid State League in your comments. I played in the Mid State League and I can confirm they did not play music during our games. Then I realized you were talking about the MLS, and that's an entirely different league all together.