When It Pays to Root for the Underdog

Last year, picking Little Rock over Purdue was a better bet than a choosing a clearly inferior Maryland squad to be upset.


The infamous 12 seed has a beaten a 5 seed in 27 of 31 years since the field expanded to 64 teams.  Over the last eight years, 12 seeds are an impressive 21-10-1 against the spread while also going 17-15 straight-up.  Despite the unlikely yet consistent success of 12 seeds, people still refuse to pick them to win.  This makes choosing a 12 seed a valuable proposition when trying to get ahead of others in your bracket pool.  But what makes these 5 seeds so vulnerable?

“The five-seed is where you lose natural geographic-area protection, because only the top-four line receives that protection,” explained Greg Shaheen, former senior vice president of the NCAA and organizer of the NCAA Division I men’s basketball championship. “Once you go to the five-[seed], you could be playing those games anywhere.”

So, has location actually mattered?  Of the 26 upsets since 2002, 16 involved 5 seeds that had to travel over 1,000 miles from campus to the first round location.  Lowering the mileage to 800 miles adds 3 more upsets.  Only one upset involved a 5 seed playing within 350 miles of their homes.  Notably, of the last 19 12-5 upsets, 11 occurred in the Mountain or Pacific time zones, and five from the state of Florida.

However, there have been a few 5 seed teams that traveled west and beat a team with regional home-court advantage.  In 2003, Wisconsin and UCONN won in Spokane versus Utah-based teams; in 2004, Syracuse beat BYU in Denver; in 2011, Kansas State defeated Utah State in Tucson; and last year, Maryland beat North Dakota State in Spokane.

The evidence may be surprising but highlights the importance of selection committee seeding when determining the top 16 teams.  This year, there are first round games in Sacramento, Salt Lake City, and Orlando.  Keep an eye on any 5-12 matchups in those locations.

The other commonly accepted tenet of a 12-5 upset is that it usually involves a mid-major over a power conference foe.  This is true – this type of upset has happened the most (10 times) since 2002.  But that is probably because it is the most common matchup between a 5 and a 12.  When looking at all of the possible chances (35), the fact is that 12 seed mid-majors upset 5 seed power teams only 28.6% of the time.

Compare that to other types of 5-12 matchups.  In the eight power vs. power 5-12 games since 2002, six were upsets.  In more recent years (2009-2016), underdog power teams have been matched up with mid-major favorites; the power teams were successful in three out of the four attempts.  That’s 75% for both types and something to watch going forward.

But we can’t stop there.  This is a perfect bracket we are talking about, after all.  Let’s dig deeper and look into Ken Pomeroy’s statistics since 2002 on these upsets to notice any trends.  Because we are trying to prognosticate what will happen, we will use the stats as they existed before each tournament began.

First, let’s see if the best 5 seeds are immune.  Looking at the adjusted Efficiency Margin rank (EM), we find that 5 seeds ranked in the top 20 account for 12 of the 26 victims.  So any 5 seed can be beat.  How about the other end, are there 12 seeds so bad that they never win?  Only five 12 seeds with an EM rank over 60 have won and none over 95.  That’s our floor then.  What about the gap in EM between the two teams?  Only half of the upsets came from teams ranked within 30 spots of the 5 seed.  The overall rank in EM does not seem to give us much information.

How about offensive versus defensive teams?  A 12 seed with a better adjusted defensive efficiency accounts for just six upsets – the same number of upsets won by a 12 seed that gave up 5-10 more points per 100 possessions and those won by a 12 seed that gave up 10 or more points per 100 possessions.  Looking at adjusted offensive efficiency provides better results.  Nearly half of the upsets (12) involved an underdog that was better on offense than the favorite.  Looking at both stats combined, we find that an underdog that was either better at offense or defense than the favorite won a remarkable 18 times.  Of the other 8 upsets where the underdog was not better in either offense or defense, the remaining 12 seeds were within 5 points per 100 possessions in at least one category and three within a point.  In sum, of the last 26 12-5 upsets, 21 (80.1%) involved a 12 seed that was better or within a point per 100 possessions in either adjusted offensive or defensive efficiency.

Based on the above analysis, here are our theories that give the best chance of a 12-5 upset (in order of what I think is most compelling):

  1. 12s seed with better or nearly equivalent adjusted offensive or defensive efficiency are more likely to take down a 5 seed.
  2. Upsets should have 12 seeds with an EM ranked 60 or better.
  3. An underdog team from a power conference is likely to win.
  4. The 5 seed is playing more than 350 miles away from their campus.
  5. The game is in a Mountain/West region or Florida.

There is still some wiggle room here but applying all of these to last year’s tournament would have shown Maryland and Indiana to be secure because their opponents were over EM rank 60 (80 and 105, respectively), Baylor at risk due to Yale’s superior defensive efficiency and EM ranked 50, and Purdue at risk playing in Denver against Little Rock with an EM ranked 59.  As stated above, any 5 can be beat.  But the worse the 12, the less likely the upset.  Little Rock still probably should not have won that game but this analysis shows why picking Purdue was riskier than a choosing a clearly inferior Maryland squad.