LAS VEGAS – As a coach, Deion Sanders is the Sphere. He is a fully immersive reality show, a bright bulb, an interactive atrium with a series on Amazon. The Big 12 Media Days opened Tuesday at Allegiant Stadium without Coach Prime. The CU Buffs meet the press on Wednesday, their time slot falling into the second half of the eight schools in the 16-team conference. Standing below a classic “Welcome to Fabulous Las Vegas” sign, showgirls greeted reporters as they walked onto the field.