Watching the parade of twinkling lights arrive in the desert, Dick Ebersol believed that the XFL—the loud, garish football league dreamt up by his friend, the pro wrestling impresario Vince McMahon—might really have a chance.

It was the league’s opening night, Feb. 3, 2001, not long before the kickoff between the host Las Vegas Outlaws and the New York/New Jersey Hitmen. Ebersol, the NBC sports boss and broadcasting legend, was high atop Sam Boyd Stadium, where he saw a ribbon of car headlights winding its way from the city...