I think that trend/stat is pretty pointless, personally-- In the playoffs, there are only eight teams you can get beat by-- 4 if you get to the second round, two if you make it to the conference finals, and one if you make it to the final.
If you're a competitive team who isn't at the bottom of the playoff teams, it isn't too unlikely/surprising to get knocked out by the eventual cup winner, IMO. Especially taking into account that the eventual cup winner is going to beat 3 out of the other 7 teams, and when you lose a round, you're increasing the chances of the team that beat you exponentially.
It's barely even a coincidence, IMO.