By the time Selection Sunday rolls around, the selection committee's job is usually fairly easy. Most of the bubble teams in contention have already played themselves out during conference tournaments, and the top of the bracket has settled for the most part.
That won't be the case this year. Even with less than 24 hours until the field is announced, there could be as many as seven or eight teams fighting for what appears to be one or two bids at the bottom of the bracket. Throw in a couple of potential bid-stealers and it's going to be a difficult stretch for the committee.