NCAA Tournament S-curve, explained: How March Madness selection committee will shape the 2021 bracket

NCAA Tournament S-curve, explained: How March Madness selection committee will shape the 2021 bracket

March Madness in 2021 may be the most accurately bracketed tournament in recent memory.

Maybe ever.

That’s because geography, in 2021 at least, won’t be a determining factor in how the selection committee places teams in specific regions; since COVID-19 has forced the entire NCAA Tournament to take place in Indiana, the committee will now rely primarily on the S-curve to come up with its 68-team bracket.

The NCAA explained its decision to use the method in a Jan. 15 news release.

“As the committee discussed this topic, it became clear that the S-curve bracketing option makes the most sense, given the unique circumstances with which this tournament will be played,” said Dan Gavitt, NCAA senior vice president of basketball. “In a normal year, bracketing is done with consideration given to keeping as many teams as close to their campus as possible, reducing team travel and providing as many fans as possible an opportunity to watch their favorite teams participate in The Big Dance. But this year only, with the entire tournament being played in Indiana, the committee believes this different approach is optimal.”

But what exactly is the S-curve? Sporting News has you covered on how it works and why it hasn’t been the primary tool for the selection committee in recent years:

MORE: NCAA selection committee has no excuse to botch 2021 bracket over geography

What is the S-curve in the NCAA Tournament?

The S-curve is a bracketing method that ranks every NCAA Tournament team, numbered one through 68, and orders them in a way that rewards the best teams along a particular seed line.

The four 1-seeds are ranked first, second, third and fourth; the four 2-seeds are ranked fifth, sixth, seventh and eighth and so on through the 16-seeds. The teams are then ordered and placed in their specific region using a snaking pattern — think of a snake draft in fantasy football — ensuring the top team in a particular seed line plays the lowest-ranked team from another seed line.

For example, the top 1-seed (No. 1 overall) would play the worst-ranked 16-seed (No. 64) in the opening round, while the lowest-ranked 1-seed (No. 4 overall) would face the strongest 16-seed (No. 61). That methodology might not matter in the earlier rounds when there’s a more pronounced disparity in talent, but it becomes more prevalent as the tournament progresses and that divide narrows.

Here’s how it would look for an entire tournament, not accounting for First Four games. (For the purposes of this article, regions will be lettered A, B, C and D; the official region names have yet to be released).

  Region A Region B Region C Region D
1-seeds 1 2 3 4
2-seeds 8 7 6 5
3-seeds 9 10 11 12
4-seeds 16 15 14 13
5-seeds 17 18 19 20
6-seeds 24 23 22 21
7-seeds 25 26 27 28
8-seeds 32 31 30 29
9-seeds 33 34 35 36
10-seeds 40 39 38 37
11-seeds 41 42 43 44
12-seeds 48 47 46 45
13-seeds 49 50 51 52
14-seeds 56 55 54 53
15-seeds 57 58 59 60
16-seeds 64 63 62 61

This method isn’t just for the 1-seeds, either. It ensures every team with a shot at winning the national championship has an appropriately difficult path to the final, based on its ranking. In the Elite Eight, for example, it’s the difference in a 2-seed having to face the top overall seed vs. the fourth-best team.

Assuming chalk won out through the first two rounds of the tournament, here’s what each region would look like heading into the Sweet 16:

Region A

  • No. 1 overall seed (1-seed line)
  • No. 8 overall seed (2-seed line)
  • No. 9 overall seed (3-seed line)
  • No. 16 overall seed (4-seed line)

Region B

  • No. 2 overall seed (1-seed line)
  • No. 7 overall seed (2-seed line)
  • No. 10 overall seed (3-seed line)
  • No. 15 overall seed (4-seed line)

Region C

  • No. 3 overall seed (1-seed line)
  • No. 6 overall seed (2-seed line)
  • No. 11 overall seed (3-seed line)
  • No. 14 overall seed (4-seed line)

Region D

  • No. 4 overall seed (1-seed line)
  • No. 5 overall seed (2-seed line)
  • No. 12 overall seed (3-seed line)
  • No. 13 overall seed (4-seed line)

Why doesn’t the selection committee always use the S-curve?

The selection committee does use the S-curve every year. But, as Gavitt noted in the NCAA’s Jan. 15 news release, it’s not the ultimate factor in how teams are bracketed; that distinction falls to geography. If the selection committee feels a team would travel an unfair distance to play in a certain regional host city — as is the case in most years — it will move said team along the seed line to make sure it has a more acceptable distance to travel.

A particularly egregious example of this occurred in 2019, when Michigan State — the second-strongest 2-seed, ranked sixth overall — was moved from the Midwest Region to the East Region. The reason? The Spartans would have had to travel 711 miles from East Lansing, Mich., to Kansas City, Mo., had it stayed in the Midwest; by moving to the East Region, the team had only to travel 591 miles to Washington, D.C.

The committee saved Michigan State from flying an additional 120 miles. It also forced the Spartans to face top overall seed Duke in the Elite Eight.

The move gave both teams a more difficult matchup earlier in the tournament, when their tournament rankings should have resulted in an “easier” regional final. It cost fans the chance to see both teams face off in the Final Four and, since Michigan State won, removed Duke freshman Zion Williamson — by far the tournament’s biggest attraction — from the field.

That won’t be an issue in 2021. The entire tournament will take place in Indiana, with the majority of games unfolding in Indianapolis.

Exceptions to the S-curve

The S-curve will be the primary bracketing method for the 2021 NCAA Tournament, but the selection committee will take several factors into account to reduce the number of regular-season rematches.

From the NCAA:

  • Each of the top four teams selected from a conference shall be placed in different regions if they are seeded on the first four lines.
  • Teams from the same conference shall not meet before the regional final if they played each other three or more times during the regular season, to include the conference tournament.
  • Teams from the same conference shall not meet before the regional semifinals if they played each other twice during the regular season, to include the conference tournament.
  • Teams from the same conference may play each other as early as the second round if they played no more than once during the regular season, to include the conference tournament.
  • If possible, rematches of nonconference regular-season games should be avoided in the First Four and first round.