The top 4 lines

I ran into a catastrophic scenario when bracketing today.

Remember there's a 4 in 4 rule?  The top 4 teams from a conference must be placed in four separate regionals, if each of the teams are top 4 seeds.  Among the top 16 overall seeds, the top 4 from each conference should be in different regionals to separate the best from playing each other too early.

Teams in my top 16, based on conference affiliation:
B1G 4 teams, ACC 4 teams, Big 12 4 teams.  And Big East 2, A-10 1, Pac-12 1.

Therefore, right away, we know each of the four regionals MUST contain exactly one B1G team, one ACC team, and one Big 12 team.  This causes a catastrophic domino effect:

1) First, place the 1 seeds in regionals.  Kansas in the South, Oklahoma in the Midwest, Villanova in the East, and Xavier in the West.  See the problem already?  The East and West regionals must have 1 B1G team, 1 ACC team, and 1 Big 12 team, but both have taken a Big East team as their fourth team already.  Therefore, Oregon, despite being the highest 3 seed, is already locked out of playing in the West regional.

2) The 2 seeds are placed in next, but because of the eastern imbalance, the West regional has the weakest 1 seed and weakest 2 seed (Michigan St in this scenario).  At this point, the combinations are Kansas/UNC, Xavier/Michigan St, Villanova/Virginia, and Oklahoma/Iowa.

3) You can see the problems already.  Oregon goes to the Midwest regional as the next highest seed, to join Oklahoma/Iowa.  Once you do this, an ACC team is forced into the regional in the 4 line, which is Duke.  This forces Miami to the west regional.  That's right, even though Miami is higher than Duke in the rankings, they get shipped all the way across the country while Duke stays relatively close to home, just because of Oregon's presence.  And once that happens, Iowa St is locked into the West regional, which locks West Virginia into the East regional.  And because WVU has to go East, Maryland gets kicked out of its preferred East regional, which kicks Purdue out of the South regional they prefer.  All of this is a nasty chain reaction that starts because Oregon got displaced because the Big East has two 1 seeds.

4) Another nasty side effect is that you can't adjust this bracket for balance.  Since everyone is forced into a specific spot, you can't adjust for imbalanced regionals.  Well, guess what happens:
- The West regional has the worst 1, 2, and 3 seeds, and the second worst 4 seed
- The Midwest regional has the second best 1 seed...and the best 2, 3, and 4 seeds
This is incredible imbalance, but there is no way to fix this without violating another rule.

5) There is exactly one fix:  a procedural bump of Xavier to the 2 line and Iowa to the 1 line.  That would be unprecedented, but this might be the one unique scenario where the committee might sell its soul to the devil.

6) Well, there might be a second fix:  Oklahoma in the West regional.

The final regionals I came up with:

SOUTH 32
Kansas
UNC
Maryland
Dayton

WEST 39
Xavier
MSU
Miami
Iowa St

EAST 36
Villanova
Virginia
West Virginia
Purdue

MIDWEST 29
Oklahoma
Iowa
Oregon
Duke