Minnesota Vikings center Ryan Kelly has retired after a concussion-marred final season in his 10-year NFL career, the team announced on Friday. Kelly played in only eight games in his lone season with the Vikings after he was part of the team’s push to invest heavily in an offensive line upgrade, giving him an $18 million contract with $9.25 million guaranteed a year ago to leave the Indianapolis Colts in free agency. The offense was noticeably more productive when Kelly was on the field in 20...