S Janzen Jackson (6-1, 190) is undersized for the position, but he’d make a big CB, which is where he practiced on Tuesday. “We expect him to learn and know both,” Coughlin said of the undrafted rookie. “We’ve kind of shuffled the numbers that way because of the corner situation and who’s practicing and who isn’t.” CB Corey Webster (hamstring) is out and CB Prince Amukamara (foot) is limited, so Jackson is seeing more time at CB.