Two forces converged one year ago when news broke that the Kansas City Chiefs would trade quarterback Alex Smith to the Washington Redskins.
The Chiefs sought value for Smith before promoting Patrick Mahomes. Washington wanted to secure Kirk Cousins' successor quickly.
The 2019 trading period will carry its own forces that could spur movement when the league opens for business in March. Conversations with NFL team executives during the buildup to Super Bowl LIII produced a few tantalizing ideas, starting with one that would send Pittsburgh Steelers wide receiver Antonio Brown to one of the teams that played well into January.