Mets GM Brodie Van Wagenen has said on multiple occasions this winter that upgrading and stablizing center field is a priority for him when building next year's roster.
The Giants, Mariners, Rockies, Rangers and White Sox have all reportedly been looking for a new center fielder as well.
The overall market for everyday outfielders, especially up the middle, has been weak.
It's always possible Van Wagenen chooses to add a corner outfielder and return to using a combination of last year's rotation in and out of center field. However, if he's looking to make a new addition, he'll likely have to choose from one of the four options.