Except when they were the Expos, yes - first as Nationals
Even as the Expos, their playoff victories were spotty. They beat the Phillies in 1981 in a division series made necessary by a baseball strike that year, otherwise they would have finished second in their division. Then they got their hearts broke by, ironically, the Dodgers on a Rick Monday homer in Game 5 at home.
In 1994, they had the best record in their division but their season was halted by another baseball strike and the postseason was cancelled with the champion vacated.
So, they made one postseason by fluke and lost another postseason by fluke. That was all they accomplished before moving to DC.
Now, Howie Kendrick can run for mayor.