“SportsCenter” remains appointment viewing for its signature segment, “Bad Beats,” a “Scared Straight” for gamblers where Scott Van Pelt, left, and sidekick Stanford Steve Coughlin riff on clips showing supposedly sure bets that go awry. But Van Pelt, who entered his 10th season this month, is still thriving as ESPN has turned his “SportsCenter” into a postgame show for its …