By Andrew Holleran The Dallas Cowboys handed Bill Belichick the worst defeat of his NFL head coaching career on Sunday. Dallas blew out New England, 38-3, on Sunday afternoon, handing him the worst margin of defeat in his 20-plus year head coaching career. Following the game, Cowboys owner Jerry Jones used one word to describe handing Belichick a historic loss. “Surreal,” he said. Jones and his Cowboys are now riding high following their difficult Week 3 loss to the Cardinals. “Surreal is what it is when you look at how well they have competed all these years, and so again that is the case whe…