The practice of playing one or two preseason exhibition games by each team before the start of the regular season was discontinued when the NBC contract was initiated, and the regular season was extended from 14 games, the length that it had been since 1996, to 16 from 2001 to 2010, and since 2016. From 2011 to 2015, the regular season league expanded to 18 games, with each team having two bye weeks and the option of two preseason games.

A contract with what television network led to the discontinuation of exhibition games in the preseason?