This Feburary, Harrison has his luggage ready for a trip to the desert.
Harrison announced his retirement in August after a visit with the Arizona Cardinals, but was back in the league less than a month later when the Pittsburgh Steelers lost two young linebackers -- Ryan Shazier and Jarvis Jones -- to injuries. Harrison filled in nicely, recording 29 solo tackles and 5.5 sacks in 11 games for a Pittsburgh team that finished 11-5 and won the AFC North.
Should he return to the Steelers, the 36-year-old could be useful as both insurance against the development of Jones -- who has flashed his ability but has yet to live up to his first-round selection -- as well as a pass-rushing machine that most offensive tackles will not be happy to face. Harrison's value could also increase if Pittsburgh can't come to an agreement on a new deal with free agent rusher Jason Worilds.
The return to the NFL was apparently enough to convince Harrison he isn't done with professional football yet. Based on his offseason workout videos, he's clearly still in great shape.