Article Photos: Oklahoma football: Why Zack Sanchez is a symbol of the Sooners' defense 1/4

Quarterbacks Cody Thomas, Trevor Knight and Justice Hansen go through drills as the University of Oklahoma Sooners (OU) begin spring practice on Owen Field at Gaylord Family-Oklahoma Memorial Stadium in Norman, Okla., on Tuesday, March 11, 2014. Photo by Steve Sisney, The Oklahoman