It wasn't just the red sweater crowd growing complacent. As this article explains (it's a bit long-winded so I'll summarize it), UW changed the way student season ticket holders get assigned seats. It's always been and remains a lottery to get student season tickets. But once you "get tickets", it used to be that you were assigned seats based on your willingness to be first in line on a particular Saturday morning in the fall. The first kids in line got first dibs on the choicest seats. That meant that really pysched students would camp out overnight, and usually resulted in the most committed students getting the seats closest to the floor. This also meant that the really loud, passionate fans were often massed together at the front of the student section.
But not this season. Instead, this school year seat selection was based on seniority, which meant that underclassmen (often the loudest fans) were exiled to the upper deck. This dispersed the core of really loud students, and apparently led to the Kohl Center being quiet as all hell for most of the season, as I've complained about earlier. The student who penned the piece I link to above claims that it cost UW the second game against Purdue, as the crowd never really got into that contest after Purdue jumped out to a sizeable lead. Not a bad argument. You only have to watch one game at Duke to realize that critical masses of loud students are a decided home court advantage. The UW ticket office should definitely tweak things so the most committed and loudest fans are clumped together and are close to the court. It helps the home court advantage, and it's good advertising and PR for the university.