Picking the top four teams to the Sweet 16 has only been right 7 times, just over 10% of tournament regions since 2002. Only about half of the top 25 kenpom teams and those teams with an adjusted efficiency margin over 25 survive the first weekend.
But if you are looking for major upsets, you should focus on the bottom half of each region. 1 seeds have only lost to eight 8/9 seeds since 2002. Only two 12 seeds have beaten a 4 seed. It is much more sensible to focus on a 2 seed and a 3 seed to fall early.
Indeed, in the last seven tournaments, seven 2 seeds and seven 3 seeds have lost in the second round. 2 seeds typically are those teams who did not win their power conference regular season title but won the conference tournament or vice versa. They are the almost-perfects, the elite but not the best.
In preparing for this post and this entire exercise of making a perfect bracket, nothing was as shocking as this factoid. In the last 15 years, there have been 14 2-seeds that won a power conference tournament – not a single one lost a second round game. Now, obviously, 2012 Missouri and 2016 Michigan St., conference tournament winners in their own right, lost in the first round in unexpected fashion. But if you see a conference tournament winner, pen them into the Sweet 16.
Conversely, 7-10 upsets have come from mid-major conference tournament winners or teams that lost in their conference’s semis or finals. Only two 7-10 upsets came from a team that lost earlier than the semis since 2002: 2011 Florida St., which lost in the quarters by 1, and 2016 Wisconsin, which lost its first game and won over Xavier on a buzzer beater.
3 seeds versus 6 or 11 seeds are a bit more unpredictable. Some 3 seeds seem so vulnerable, it feels like they should lose, but they don’t: like 2013 Florida, which went 1-7 in “A” rated games according to kenpom, or 2015 Oklahoma, which had two losses to teams that finished the year ranked 80th or worse in adjusted efficiency margin. Other 3 seeds seem so strong, they should not lose but did: 2014 Creighton which had no bad or “B” rated losses. Only about 62% of 3-6 matchups since 2002 resulted in the better team on kenpom winning. Add in 11 seeds and that percentage barely rises to 67%. Good, but we need more data.
The only consistent trend that I can see comes from a smaller sample size. Of the last seven 3 seeds to have fallen, only one lost to defensively focused opponent – an over-ranked 2012 Florida St. team.
Next up is the seemingly trickier 4-5 matchup. In looking at the data, picking the favorite in kenpom works more often than not and when it doesn’t, it has usually been because the underdog’s defense or offense was better (numbers favor defense slightly more). Very rarely did I see an underdog 4 or 5 beat a similarly composited opponent. Beyond that, it becomes tough call. However, keep in mind that about half of all regions since 2002 have involved a second round matchup that wasn’t a 4-5 seed affair. Selecting a 12 or 13 seed to win the first round game should make this second round choice easier.
Finally, we have 1’s versus 8’s and 9’s. As stated near the top of this post, this type of upset is pretty rare but it used to be rarer. Five 8/9-1 seed upsets have occurred since 2010. Compare that to 2005-2009 when there were four straight tournaments without a second round upset of a 1 seed. Three of recent upset winners were mid-majors, three offensive-focused, four out of five were in their conference tournament final, all five ranked in the top 45 teams, all five played an opponent rated 7th overall or better with a top 15 offense in kenpom, and all five had at least eight “A” or “B” ranked wins. So while it is unlikely that a 1 seed will fall, it has been happening consistently as of late. Another loss in the second round this year would solidify this type of upset as something that has to be included in a perfect bracket attempt going forward.