<div class='quotetop'>QUOTE </div><div class='quotemain'>Shelton Quarles-LB- Buccaneers Mar. 2 - 9:56 am et Shelton Quarles disclosed Thursday that doctors have advised him to retire because of concussion problems.Quarles reportedly had six concussions during the 2005 season, in which he didn't miss a single game. If he retires, Barrett Ruud should take over in the middle for Tampa.</div>Sad....