March Madness 2021: Most under-seeded and over-seeded teams in NCAA Tournament bracket

Using net efficiency margin to determine which teams are under-seeded and over-seeded in the 2021 March Madness bracket.

The 2021 NCAA Tournament bracket is finally here. At long last, we have a bracket to analyze and speculate over in the coming days, and we’re here to help you win your bracket pool.

In short, not all seeds are equal. The selection committee gathers several data points and the almighty “eye test” to seed and select 68 teams for the bracket, which causes certain teams to appear stronger or weaker than efficiency metrics would suggest.

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Using data from KenPom.com, we compared the net adjusted efficiency margin of this year’s field of 68 to the average net adjusted efficiency margins of each of the 16 seed lines from the past seven tournaments.

This analysis shows which teams might be undervalued or overvalued by the selection committee and could help you earn valuable points in your bracket.

Let’s start with the average adjusted efficiency margin by seed from the past seven tournaments for each seed. The margin indicates how many points per 100 possessions a team is better or worse than the average team.

Average efficiency margin by seed, 2013-2019

• No. 1: 29.36
• No. 2: 26.38
• No. 3: 23.42
• No. 4: 22.20
• No. 5: 20.71
• No. 6: 18.67
• No. 7: 18.09
• No. 8: 16.66
• No. 9: 15.57
• No. 10: 15.91
• No. 11: 15.34
• No. 12: 12.50
• No. 13: 8.35
• No. 14: 6.30
• No. 15: 2.62
• No. 16: -2.97

Under-seeded teams

While it might be hard to believe, No. 1 seed Gonzaga enters the field of 68 with the highest positive differential in adjusted efficiency margin vs. its seed. The Bulldogs have been that dominant on both sides of the ball and should enter the tournament as firm favorites to cut down the nets.

Further down the list, things get interesting. The Loyola Chicago Ramblers picked up a No. 8 seed despite the 9th-best adjusted efficiency margin among the 68 teams. Porter Moser’s squad could be another Cinderella favorite.

Searching for an upset? Colgate and Abilene Christian could be worth a look. Both squads have efficiency margins much higher than typical No. 14 seeds.

Over-seeded teams

A program familiar with being under-seeded, Wichita State enters the 2021 tournament as the most over-seeded team in the field as a No. 11 seed. The Shockers sneaked into the field and will face Drake in a First Four matchup on Thursday, March 18.

Elsewhere, four Big 12 teams make the list with Oklahoma State, West Virginia, Texas and Kansas all among the top 10 teams with the largest negative differential in adjusted efficiency margin vs. its average seed.