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How the College Basketball Bubble Works

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This time of year we hear fans lament of teams on the bubble where every win solidifies their case to be in the tournament or every loss eliminates them from hope. Is that really the case? Let’s look at how the bubble really works.

The NCAA tournament is made up of 32 automatic qualifiers that represent the tournament champion of each of the 32 Division I conferences. The remainder of the field, 36 at-large teams, are chosen by the NCAA selection committee using this criteria. It seems easy enough. Find the 36 best teams that didn’t win their conference tournament, but the last part of that sentence is what changes the dynamic of the bubble.

Let’s take a look at our most recent All 351 Rating.  Aside from Oklahoma State (we’ll look at their case separately), the first 36 teams will almost assuredly be in the NCAA tournament.  These are locks. Some of these 36 teams some will win their conference tournament. Based on our rating that number is 10. So we have identified 25 at-large teams. We need to find the next 11. Let’s move 11 rows down the list. We find one more conference champion, Middle Tennessee St. (remember that name). We continue down our list until we have 36 at-large teams which make our current bracket. We now have accounted for 11 of the 32 conference champions. The other 21 conference champions fall outside our list. These 21 conferences, will be one bid leagues only and have no bearing on the bubble.

Jump forward to Championship Week. Starting March 4 and running through Selection Sunday, March 12 each conference automatic bid will be determined. This is when the bubble gets interesting. Use the First and Fan All 351 data to create you own at-large list. The first thing to know is, the bubble can only shrink. It cannot grow because as teams outside our at-large list win conference tournaments, that means the highest team on the list that we thought would get an automatic bid now gets the at-large bid and the bubble decreases by one. The second thing to know is for every action there an equal and opposite reaction. That is, if a team moves up the list, someone must move down. Quite often it’s a team that’s not even playing.

Let’s take a look at some scenarios. Remember we only need to consider these conferences: The Big East, Big 12, Atlantic Coast, West Coast, Southeastern, Pac-12, Big Ten, American, Missouri Valley, Atlantic 10, and Conference USA. All others, including the Mountain West, are one bid leagues this year.

In the six major conferences, rarely does a team outside our at-large list win a tournament, but often a team needing a couple “good wins” pulls an upset or two that moves them up the list. When that happens other teams are moving down. On the Thursday and Friday of Championship Week, when the major conferences get into their respective quarterfinals, every game is having this volatile effect. The net result is very unpredictable. Once the major conference tournaments reach the semi-finals the volatility subsides, but if teams outside the at-large list keep winning, changes keep occurring.

In the West Coast, American, Missouri Valley, and Atlantic 10, all should expect at least 2 teams in the tourney – Gonzaga and St. Mary’s in the West Coas, Cincinnati and SMU in the American, Wichita St. and Illinois St. in the Missouri Valley, and Dayton and VCU in the Atlantic 10. As long as one of those two teams wins the conference tournament, there will be little impact to the bubble. If another team reach the conference final, particularly Houston in the American and Rhode Island in the A-10, the same dynamic mentioned above occurs, and the team that gets bumped out is probably no longer alive in their tournament.

The most interesting case is that of Conference USA and Middle Tennessee St. If MTSU wins the C-USA tournament, C-USA is a one team league. Right now Middle Tennessee St. would be in the Last Four In category if they are not a conference champion, but if they are not a conference champion that means they lost to a team rated much lower, and might bump them off the at-large list. The net result is bubble teams need one of two things to happen: Either MTSU continues to stay hot and wins the tournament (no effect on the bubble) or MTSU begins to lose several conference games and lose in their tournament (MTSU falls out of bubble contention).

Now let’s address Oklahoma St. Since the tournament expanded to 68 teams, no at-large bid has been given to a team with a conference winning percentage below .380. As of Feb. 10, Oklahoma St. is 4-7 in the Big 12 or .364. All of the national rating systems have the Cowboys in the top 30 teams in the nation, including the RPI which historically has influenced the committee the most. Under normal circumstances OSU should be a top 8 seed. First and Fan has safe guards to eliminate teams from the bracket with winning percentages below .350. Clemson falls into this category. How the committee views Oklahoma St. will have another significant impact on the bubble.

From the latest bracket, here are the bubble teams:

Last four in:
Rhode Island
Virginia Tech
Michigan St.

First four out:

Next four out: