The bracket and teams from same conference

I always thought (no proof) that there was a guideline with the bracket committee that teams from the same conference wouldn't be seeded in the same half of a regional bracket unless more than 8 teams from that conference made the tournament. In other words, two teams from the same conference would not meet before the regional final.

However, here we have Purdue and Michigan State potentially meeting in the regional semifinal this year...with only 7 teams from the conference in.

Did that happen because our seeds aren't spread across the spectrum like usual? Normally we'll have 7-8 teams evenly distributed among seeds 1-8/9, but this year we've got 7 teams crammed between 4 and 9 seeds?

I think you answered your own question.

4,5,6,7,8,8,9

Log Jam City

Yeah, and given that a region's 4, 5, 8 and 9 seeds all collide in the regional semifinal, having 5 teams fit into those seeds means it's unavoidable.

Unless they adjust seeding to avoid that, but apparently seeding is more important than avoiding it.

The regional semi-final is the Sweet Sixteen right? I think teams from the same conference can meet there, but no earlier. Likewise I think the first round cannot have rematches, so for example, we could not have played Vanderbilt or Arkansas in the first round, but we could have met in the round of 32.

I found an actual rulebook the NCAA uses.

The applicable rules:

- Teams from the same conference shall not meet prior to the regional final if they played each other three or more times during the regular season and conference tournament.

- Teams from the same conference shall not meet prior to the regional semifinals if they played each other twice during the regular season.

- Teams from the same conference may play each other as early as the second round if they played more than once during the regular season and conference tournament.

- Any principle can be relaxed if two or more teams from the same conference are among the last four at-large seeded teams participating in the First Four.

- A team may be moved up or down one (or in extraordinary circumstances) two lines from its true seed line when it is placed in the bracket if necessary to meet the principles.

They recently changed it. Your thought was correct a year or two ago

They've backed off that stance.

About 2001-2002 they started prioritizing keeping teams closer to home.
About 2-5 years ago, they started allowing lower seeds to be in the same bracket with a greater reliance on the "S" curve.

They also tried to avoid regular season matchups, but if Arkansas would upset N.C, we'd face them in the Sweet Sixteen. This also started to trend away in recent years in favor of sticking to S curve seeding.