On paper, a 6 seed losing to an 11 seed is an upset. In reality, when the oddsmakers pick the 11 seed as the favorite, it's not really an upset.
San Diego State came into their second round game today with North Carolina State with a shiny number 6 seed, but also as a 2 point underdog by the sports books. The Aztecs promptly got bounced 79-65. SDSU was expected to be one of the mid-majors with a shot to go deep in the tourney, but after their lackluster performance in the Mountain West Tournament, this really isn't a surprise.
Remember, the people who set the lines in Vegas actually know a little bit about what they're talking about.