It starts at 12:20 p.m. this afternoon. Tip-off. For some, the pinnacle of sports fandom rests in these next few days. They are epic: 12 hour days that capture some of the very reasons why we watch sports. The NCAA Tournament has the most exhaustive field in major U.S. sports, giving 65 teams a shot at glory in the national spotlight. Year after year, the Big Dance provides buzzer beaters, star turns, Cinderella stories and…