Will an undefeated team be sent home from 2019 USTA League Nationals? 18 & Over 4.0 men are as likely as ever

With the new format for Nationals started in 2018 and continued this year, it has always been possible for five teams to finish undefeated, and then one of them would not make the semi-finals and be sent home.  In fact, because the USTA does create an optimal schedule, there has sometimes been the theoretical chance of six undefeated and two being sent home!

Now, the chances have always been quite slim, typically less than 1% and even in the more probably cases, low single digit chances.  And it has not happened to date.  But when there is even a 1% chance of something happening, take enough samples and it will happen.

After day 1 of the 18 & Over 4.0 men's event this weekend, it looks like we are seeing the best chance yet of this controversial finish.

As I write this, six teams are all 2-0: Eastern, Southern Cal, Intermountain, Texas, Middle States, and Midwest.  Looking at the remaining schedule, only Eastern and Midwest play each other, so it is entirely possible, and perhaps probable, that five finish undefeated!

Now, my simulation said going into the event that there was a 4% chance of there being five undefeated, about as high as we've ever seen.  As we enter day 2, the simulation says it is now a 12% chance.

Why isn't it higher?

First, there are some strong teams outside of the six 2-0 teams that must still be played, and tennis is a sport where match-ups matter, and who actually plays matters too, they are not simply won by the team with the higher top-11 average.  "Anything can happen", and for it to happen here, five teams would have to all go 2-0, just one slip up and it doesn't happen.

Second, the teams may not all even be favored to win.  I already noted Eastern and Midwest play so one will lose, but Eastern also has to play Florida who is a strong team and is only 0-2 because they had a brutal schedule of playing Middle States and Texas and lost both 3-2.

However, it appears Florida has not played two of their stronger players, perhaps they were unavailable and couldn't make the trip, and this would mean they aren't quite as strong and Eastern very well may be favored.  If this is the case, the chances of five undefeated may go up significantly.

If it happens, then it comes down to tie-breakers, and as I've written before, they are somewhat broken and may not identify the most deserving team.  The irony of the USTA not adopting my suggested regulations change to fix the tie-breakers and then having them send the wrong undefeated team home would be classic.

Will it happen?  We'll know in a few hours!

Note: Middle States was upset 3-2 so this did not happen, but the 18 & Over 4.5 men may still finish with five undefeated.