Taken from this...This is the first time the last four at-large teams will be revealed publicly. Traditionally, the at-large teams are scattered throughout the seeding process, rarely going past No. 12, making it relatively easy to identify them. Yet the committee now will formally announce the last at-large teams by putting them in the first round.
Guerrero and Shaheen said the last four at-large teams would be put on the seed line the committee decided they earned. So, this could mean that two could be considered No. 12 seeds playing for the right to play a No. 5 and two could be No. 11s vying to play a No. 6 in the second round.
In its news release, the NCAA listed the 10th seed as a possible destination for the last at-large teams, something that has occurred in past years. It is unlikely that the committee will have one team seeded 10th, 11th or 12th to avoid having teams seeded differently playing in a First Four game.
http://sports.espn.go.com/ncb/news/story?id=5374116