Stoke City v Sunderland

Premier league, 4th February 2012, Stoke 0 Sunderland 1

WHAT ON EARTH. Why have Sunderland beaten Stoke when Stoke are at home? It is unbeliveable. Tony Pulis (Stoke City manager) was very dissapointed with Stoke today. Stoke city had a better possesion and had more shots, corners and fouls.
Why did Stoke lose?