Kelvin Sampson said there is no player in the country more valuable to his team than Jamal Shead is to Houston. Shead is the Big 12 player of the year, a first-team All-American and Houston’s best defender.The Cougars, the top seed in the South Region, played without Shead for much of their Sweet 16 loss to fourth-seeded Duke. Shead played 13 minutes in the first half and scored two points before spraining his ankle.He didn’t return to the game, watching the second half from the bench as Houston lost 54-51. Duke moves on to Sunday’s Elite Eight game against NC State.