Playing with form or genre can be risky because it might bring negative feedback or an unwanted shift in audience expectation. One example that comes to mind is when college football decided to shift their playoff bracket. Instead of allowing only 4 teams, the board allowed 12 teams to compete in the playoff, with an end goal to win a championship. This caused some controversy and it violated audience expectations, because only 4 teams had been allowed for a long time. I believe it was successful however, because the sport still brought in millions of views this past season.
This is a very good example. Sports often play with form and it upsets many people, but ultimately brings more money to the sport.