In my estimation and I could be wrong, Harper will be a free agent after the 2017 season. He has been in the majors since 2012 so this is his fourth year...a team controls their players for 6 years. So 6 years of control for the Nats will end after the 2017 season. I don't think the Yankees will be big players in the free agent market in the near future, but they will go hard after Harper. This guy is capable of hitting 60 HRs playing for them.