Okay, now that I've calm down, I realized the best analogy I can make with this. Which also happens to involve another holiday season Disney release, granted one from 21 years ago.
Now, I know we all credit The Little Mermaid with kicking off the Disney Animation renaissance that we had in the 1990's. But realize the movie wasn't a huge hit when it came out. Heck, on it's opening weekend it opened at #3 behind some Eddie Murphy movie and Look Who's Talking. All in all, it made about $84 million during it's run. It certainly wasn't Disney's highest grossing release that year - and even if it sold the same number of tickets in 2010 it would be around #15 on the highest grossing movies of that year, just edging out Grown Ups. But the movie made most of it's impact on the merchandise front those first few months. Every little girl had to have an Ariel doll that Christmas and a result, merchandise exploded even if the movie itself didn't set the box office ablaze. And then when the video came out, it sent VHS selling records that year. I anticipate a similar thing happening with The Muppets. Underwhelming box office but ridiculously strong merchandise and DVD and Blu-ray sales. Disney's good in that department.