MIAMI (AP) — Pro Football Hall of Fame center Jim Langer, who was literally in the middle of the Miami Dolphins’ 1972 perfect season, has died at the age of 71. Langer died Thursday at a Coon Rapids, Minnesota, hospital near his home of a sudden heart-related problem, said his wife, Linda. Langer was a first-year starter and played every offensive down for the NFL’s only unbeaten, untied team…