You might want to follow along with a sample scenario – https://goo.gl/Zc38am (CHN You are the Committee)
Harvard getting to #1 overall is possible, though not very likely. The Crimson only advance to #1 in about 2% of the scenarios in which they win the ECAC tournament.
Poor performance by Minnesota-Duluth and Denver is obviously required for Harvard to be able to overtake each in RPI. Each needs to lose their opener, but they then would meet in a consolation game in which both can’t lose. Duluth must defeat Denver in that game to knock Denver’s RPI just a hair below Harvard’s, while not allowing Duluth to climb enough to overtake Harvard.
Even if Duluth and Denver both lose their semifinal games and the Bulldogs lose the consolation game, Harvard still only advances to #1 in about 11% of those scenarios. Other tournament outcomes then need to push Harvard’s RPI up enough to catch Denver, but there’s no single linchpin team or game that would do it, it will take a lucky combination of outcomes. I’ll post updates throughout the tournament as the odds change.