The pie-faced Justin Maxwell sent the Nationals out on a high note. (AP Photo/Manuel Balce Ceneta) Nationals 7, Mets 4: Someone of relative importance somewhere told me that it’s not how you start, it’s how you finish. (It was probably Gorilla Monsoon during one of his patented back-and-forths with Bobby Heenan in the early 90s heyday of professional wrestling. Never the less!) For the Nationals, that platitude is slightly empty; this is a team…