Longtime ESPN “SportsCenter” host Steve Levy has a good grasp of the innovative rules that will differentiate the XFL from other brands of football, and that stakeholders hope create a more appealing entertainment product than the short-lived first incarnation of the league. Part of Levy’s job as the XFL’s lead play-by-play man for the 2020 season, which kicks off Saturday at 2 p.m. on ABC, will be explaining the eight-team league’s various quirks to viewers during the course of an up-tempo broadcast featuring all sorts of bells and whistles.