College basketball nation didn’t wait for the calendar to flip to March to start the madness. A little insanity seeped into February, as this past weekend delivered a few major upsets and several incredible games. Many teams already seem to be playing as if they’re in elimination games. And for some of our bubble teams, that might just be true.

During the final weekend of February, the top three teams in the polls lost. Upsets and inconsistency wreaked havoc among the teams in the projected field, causing upheaval in the fourth installment of the Mock Tournament brackets.

For the first time, we have movement at every seed level that involves at-large teams. That includes a new No. 1 seed in Duke, which simply keeps winning — something that most of the Blue Devils’ elite compatriots can’t claim. Purdue fizzled in its first game without Robbie Hummel, who is done for the year with a torn ACL. The Boilermakers have games remaining against Indiana and Penn State, which they should win. If they falter against two of the Big Ten’s weakest opponents, the team could slip as low as a No. 3 or 4 seed.

The weekend’s big winner was the Big 12. Specifically, Baylor, Texas A&M and Oklahoma State notched chest-puffing wins against tough conference opponents and subsequently inched higher in projected seeding. Oklahoma State made the biggest leap, vaulting the Bears and Aggies to claim a No. 4 seed. The Cowboys looked impressive in dismantling Kansas Saturday.

However, Oklahoma State’s place among the top 16 teams is tenuous, especially with a midweek game at Texas A&M looming. The Aggies have not lost to any team not nicknamed the Jayhawks in College Station this season. And projected to be a No. 5 seed, Texas A&M is probably itching for an opportunity to pick up another high-quality win and take Oklahoma State’s spot among the top four seeds.

Among the teams just making or missing the tournament, Rhode Island fell the hardest after losing at St. Bonaventure, which benefited Florida. The Gators are making their debut in the Mock Tournament’s field. Here’s some more bubble talk.

• Cincinnati remains in the field but can probably afford to lose only one more game between now and Selection Sunday.
• A few Atlantic 10 teams, specifically Charlotte, Dayton and Rhode Island, have picked a bad time to lose their mojo.
• Don’t look now, but Washington is starting to make a case for a second bid out of the Pac-10.
• Notre Dame might want to keep Luke Harangody sidelined for a while longer if the Fighting Irish continue to win. They are one more high-quality win away from entering the field.

Check out the first three Mock Tournaments to see the evolution of the projected field.

Mock Tournament 1.0
Mock Tournament 2.0
Mock Tournament 3.0

As always, share your thoughts by leaving a comment. Starting Friday, the Mock Tournament will extend its projections to include regions and pod assignments.