Could these 'mystery teams' be in on Manny Machado, Bryce Harper?

Are the Yankees set to swoop in on Manny Machado after all? Who might be biding their time for Bryce Harper? We look at some of the potential surprise suitors insiders are talking about. AP Photo/Seth Wenig

Whenever negotiations for big-name free agents drag out, in the way they have for Bryce Harper and Manny Machado, inevitably the mystery team is invoked. Maybe it's based on speculation, as competing agents and club executives and reporters trade guesses about whether a team is quietly stalking to add a star.

And sometimes, the mystery team is very real, perhaps because of some hidden development, or because an owner or general manager becomes enamored of a strong talent lingering unsigned.

Executives and agents and analysts are privately swapping thoughts on which team, if any, might be poised to strike for Harper or Machado.