Field of 64 — Who Makes the NCAA Tournament
Which 64 teams the committee should pick, who hosts the 16 regional sites, and how the 1/2/3/4 seeds line up. Updated daily through Selection Monday. Once the field is set, see CWS Odds for the Monte Carlo on who wins Omaha.
How the projection is built
Three stages. A gradient-boosted classifier scores every D1 team's resume on Selection Day; the top 64 by probability is the projected field. A second model ranks that field for the top-16 national seeds. A constraint solver then assigns the 2/3/4 seeds to each regional under two rules: same-conference teams go in different regionals, and 3/4 seeds get placed by geography. Baseball America and D1Baseball maintain their own human-judged projections that we ingest each day for comparison.
Selection day is the Monday after the conference tournaments finish — once the real bracket lands, the McConnellMargin column is replaced by the actual NCAA field.
Accuracy on the historical record
On the eight years 2016-2024 (skipping the 2020 COVID year), leave-one-year-out testing puts the at-large model at a 76% hit rate (standard deviation 3.5 points). Best year 2018 at 81%, worst 2021 at 69%. Top-16 seed overlap averages 73%. Public bracketologists at Baseball America and D1Baseball hit around 85-90% — the ~10-point gap is the editorial layer (injuries, coach turnover, momentum, conference reputation) that the resume vector alone doesn't see.