You asked if MLB had a history department or something of that nature...that’s what the media would use...didn’t realize you wanted an actual address...
long shot but might give you a lead is to reach out to Mets PR guy Jay Horwitz...he is a Clifton, NJ native, very friendly and approachable and now runs Mets alumni department....
Media Relations Department (his former department)
(718)565-4330
[email protected]
Twitter: @Jay_HorwitzPR
there is also a MLB players alumni association:
[email protected]
(719)477-1870
Major League Baseball Players Alumni Association
1631 Mesa Ave.
Copper Building, Suite D
Colorado Springs, CO 80906