On the morning of the Ravens' first training camp practice, starting center candidate John Urschel abruptly retired. Early in training camp, rookie fourth-round guard Nico Siragusa tore up his knee, costing the Ravens a potential top interior reserve. Starting left guard Alex Lewis had shoulder surgery in the preseason and was done for the year. Starting right guard Marshal Yanda, perhaps the best player at his position in the NFL, suffered a season-ending ankle fracture in Week 2. Matt Skura, who went from the practice squad to the starting right guard, is now sidelined after spraining his knee against the Raiders.