Baseball Diplomacy Act This bill waives various embargo and immigration restrictions in order to allow Cuban nationals to enter the United States to play organized professional baseball. U.S. embargo authority may not regulate or prohibit various transactions by or on behalf of such a Cuban national, nor may the individual be prohibited from returning to Cuba with the earnings made from playing professional baseball. The President's authority to bar an alien whose entry is deemed to be detrimental to U.S. interests may not be used to deny a visa to a Cuban national entering to play baseball. Such an individual may obtain a visa to remain in the United States only for the duration of the baseball season. The visa need not be renewed for reentry into the United States during the term of a contract between the individual and the team for which the individual played in the preceding season.