Simulating 2019 USTA League Nationals - 18 & Over 4.5 Women

As I did last year, I will be doing simulations of each Nationals to predict who the most likely four teams are to make the semi-finals, and also look at other interesting things that may occur.  Last year, the simulations did a pretty good job predicting who would advance to the semis including having all four teams predicted correctly several times.

Why do these simulations you ask?  The primary reason is that the format for USTA League Nationals is now a flight-less random round-robin where each team plays four other random opponents.  This introduces significant variations in schedule strength, the possibility of an undefeated team not making the top-4, and teams vying for the top-4 perhaps not having played head-to-head and unfortunate tie-breakers being used.  The simulations aim to educate folks on how it all works and look at what may happen.  Also see this write-up for some things to know about Nationals.

The third weekend of Nationals is just four days from the writing of this preview, the 18 & Over 4.5 women's event being held in Surprise, AZ.  Here is what the simulation says is likely to happen.

Note that there are just 16 teams at this event, Caribbean appears to not be sending a team.

As a reminder, my simulations are done using my Estimated Dynamic NTRP Ratings and looking at the average rating for the top group of players on each team, the actual schedule each team will play, and then doing a million simulations of the matches with some random variation in each team's expected result.

First, with 16 teams playing a random four opponents, there is less theoretical chance of five (or more) undefeated teams.  But, with the schedule in place my simulation says the there still is a chance of six(!) undefeated as well as five, but there is still just a 4% chance of even four undefeated.

In fact, there is only at 25% chance of three undefeated, which leaves a very good chance, 93%, that there will be a tie for the last spot and it come down to tie-breakers.  That tie could be two teams at 4-0 but more likely 3-1.  The most likely size of the tie is four at 30%, but there is a 23% chance of a three or five team tie, 12% of six teams, and just 7% chance of two teams.  The chances of larger ties diminish pretty quickly, but an 11-way tie is theoretically possible.

Should there be a tie on team record, it comes down first to who has the best court record, then head-to-head (if applicable), then to who lost the fewest sets, then who lost the fewest games, and finally percent of games won.  There is a 30% chance it comes down to the sets lost tie-breaker, and there is a 64% chance that is between two teams but a 29% chance it is between three teams, and 6% it is four.

The schedule strengths do vary a lot, the team with the easiest schedule having an opponent average of 4.39 while the team with the toughest schedule having an opponent average of 4.57, a 0.18 spread.  That can clearly lead to an easier road for some teams than others, in fact the two strongest teams got both a tougher and easier schedule.

So who is most likely to come out in the top-4?  NorCal, SoCal, Northern, and Middle States head the list, NorCal/SoCal being co-favorites.  But Florida and Texas are very close with Intermountain lurking along with Southern and Mid-Atlantic.  These teams could all be vying for a spot in a big tie.

For those interested, I offer a variety of reports to make Nationals more fun and help captains prepare.  I have a Simulation Report that has all of the details of the simulation including the average ratings for each team, each team's schedule strength, the most likely record for each team, and the chance of each possible record for each team.  I also offer reports to help teams scout opponents in more detail, both a Flight Report with full roster averages, top-8 averages and played by court averages for each team, as well as full Team Reports with detailed ratings for each rostered player and stats who who plays with who and on which court and how they do together.  Contact me if interested in any of these reports.