ESPN’s Bracketology efforts are focused on projecting the NCAA tournament field just as we expect the NCAA Division I basketball committee to select the field in March. ESPN bracketologist Joe Lunardi uses the same data points favored by the committee, including strength of schedule and other season-long indicators, including the NET and team-sheet data similar to what is available to the NCAA, in his projections of the field. Visit the NCAA’s website for a fuller understanding of NCAA selection criteria.
The 68-team bracket is the standard version of the NCAA tournament field that has been in place since 2011. If the 2021 field is comprised of 68 teams, there will be some key differences to past years, however.
The primary adjustment from a normal year is, of course, the playing of the entire NCAA tournament at a single site. This eliminates the need for geographical considerations in seeding. Additionally, there will be at least one fewer automatic qualifier this season, as the Ivy League’s decision to forgo the 2020-21 season reduces the number of AQ entries to 31 for this season.
In this projection, a condensed selection process would reduce the field by 10 at-large teams and 10 automatic qualifiers (the latter of which still receive a revenue unit). The top four seeds in each region would receive a bye into the second round, with four first-round games per region – 5 vs. 12, 6 vs. 11, 7 vs. 10 and 8 vs. 9 – being played without fans on the higher seed’s home court.
To minimize travel, first-round pairings will be guided by geography to the greatest extent possible. And the reduced field results in only 32 teams competing at the central site. All participants must post a minimum .500 conference record – the “Lunardi Rule” – for at-large consideration.
In this projection, the committee selects and seeds the 16 best available teams. There are no automatic qualifiers, although all non-competing conference champions receive the designated revenue unit.
To maintain some sense of national balance, conference participation is capped at four teams. And no region shall have more than one team from the same conference.
original source: NCAA Bracketology: Where does the bracket stand ahead of Champ Week?