Longtime MLB exec Bob Boone -- Aaron Boone's famous father -- is leaving his job with the Washington Nationals ... and it's all 'cause the team has made COVID vaccines mandatory.
ESPN reported the news Wednesday ... explaining Bob -- a key front-office advisor for the team for YEARS -- is not willing to comply with the Nats' new policy that all non-playing employees must get the vaccine.
It's a huge deal -- 73-year-old Bob has been with the org. since 2005 .