Another unflighted round-robin disaster in the making at Florida Mixed Sectionals

A reader gave me a heads up (thanks!) about the Florida 18 & Over Mixed Sectionals this weekend, specifically that one of the flights has the "random" round-robin format perhaps not so random.

In the 9.0 flight there are 10 teams and the teams are playing four matches each.  There should be no problem with this.  USTA League Nationals have 17 teams and the play four matches, and while there is a chance that five (or more) teams could finish undefeated, the chance is usually small, so having just 10 teams there should be no issue right?

Well, Florida is as I understand it taking just the top-2 teams while Nationals takes the top-4 teams.  But worse, if you botch the random opponent assignments, things can go really bad.  And it appears that may be the case for the 9.0 flight this weekend.

I've run the event through my simulation there astoundingly there is a chance that five teams could finish undefeated.  At Nationals with 17 teams the chances of five undefeated teams are always non-zero, but usually less than 1%.  For this Florida Sectionals with just 10 teams, the chance of five undefeated is over 1%.  Since they are taking the top-2 to the final, this means it is possible that three undefeated teams could be sent home!

Ok, but it is just over 1%, that is unlikely, what is the big deal?

Well, the chances of four undefeated teams is 9% and three is 25%!  That means there is a 35% chance that at least one undefeated team is sent home without a chance to advance to Nationals.

How can this happen?  While it is possible a truly random schedule would result in this, it would seem that somehow the stronger teams don't play each other, but each one plays all of the weaker teams.  For example, if you had the five strongest teams in one "pod" and the five weaker teams in another, you could create a schedule where each of the teams from the strong pod play four teams in the weak pod but never play each other.  I have no idea if this is what was done or not, but if so, someone seriously dropped the ball as that is a worst case scenario for this to happen.  If there is any kind of disparity between the stronger/weaker teams, there is a real chance the strong pod all goes undefeated.

This sort of thing has happened before.  Southern Cal Sectionals earlier this year had a 10 team flight playing just three matches and three teams finished undefeated and only the top-2 advanced.  And a few years ago Northern Cal Sectionals had 22 teams only playing three matches and while they took the top-4 to semis, there were five undefeated teams.  I'm pretty sure it has happened elsewhere too.

This is a call out to National to educate the sections on how to properly do unflighted round-robin.  And this is also a call out to the sections to think about what you are doing the vet the schedule that is spit out of whatever random selection it is doing.  If it doesn't make sense, do it over.