It appears that the final spread is Michigan being favored at 5.5 over Washington. That's a full point over the opening line. Even if it hadn't closed at 5.5 in favor of the Big 10 & Rose Bowl Champions, I would have stuck with the Wolverines for the win. For what it's worth, there was a forecast early on New Year's Day that had Michigan favored by 7.5 over Washington. This was before the CFB Playoff semis started.
I could totally see Washington winning outright, and even if that doesn't happen, they'll fall short to where they cover. Earlier in the season I had Michigan losing to LSU. While I often stick with the team I picked preseason, I probably don't stick with the losing team I picked preseason. Especially one that conquered Ohio State to close winning a half dozen games sans their head coach. Washington can score; Michigan can succeed offensively too. They're great defensively; at least most times Washington didn't need to stop anyone. I don't know if a see them doing so to the point of victory.
I don't think it'll be a 65-7 victory for Michigan, or even a 42-20 score. I feel like a great game closing with Michigan winning with room to spare (meaning one more max score from the Pac-12 & Sugar Bowl champions pull to within 3 but no tie game).
So if all goes well for Michigan, you'll see the CFB Four-Team Era end the way it started. A Big 10 school knocking off Alabama before a game where they won the Natty after defeating a Pac-12 program.