Why would the Mets be acquiring him? He's what at this point, a 1B? Maybe an OF? We have a 1B in Gonzalez who is playing somewhat passably, and his platoon partner would be Flores. In the OF, they have Bruce, Conforto, Nimmo who is breaking out, Cespedes coming back plus Joey Bats, who is our current over-the-hill waste of a roster spot. There's not even anywhere for Hanley to play. Even if you thought he can still play 3B, the Mets have that covered with Flores and Guillorme until Frazier is back.
I know this would be one of those "haha the Mets suck and always sign trash" things, but there's no need for Hanley. The only way I'd do it is if I first disposed of Bautista.