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ACC Women’s Preview: Beyond the Psych Sheet

The ACC women’s psych sheets have been released (our summary). This allows us to speculate about the outcome of the meet. The first step is to limit swimmers to their top 3 events (they are allowed to enter 5 and scratch down to 3 at the meet) and score the psych sheet out. This produces:

Psych Sheet Points
Louisville 1279
Virginia 974
NC State 744
North Carolina 695
Duke 626
Virginia Tech 584
Notre Dame 577
Florida State 491
Pittsburgh 412
Georgia Tech 377
Miami 213
Boston College 150

The biggest flaw is that the divers are currently unranked. Every diver has a score of “NP” so diving isn’t included in the scored psych sheet. This means that this ranking gives us a nice baseline, but it’s not very different from where the Swimulator top times ACC rankings have been for the last month (a more in depth breakdown).

We know for certain that swimmer’s times will change a lot at the meet. Some psych sheet ranks are rock solid in the face of large changes (ex. teams with lots of swimmers who’ll likely never miss finals or ever score) where as others are illusions disrupted by small time changes (ex. teams that are over seeded or have many middle of the pack swimmers with seeds vulnerable to small time swings). We can gain some insight into the stability of each team’s ranking by running Monte Carlo simulations of the meet with differing assumptions. How each of these will work:

  1. Remove swimmers from all events except their top 3 ranked events
  2. Modify each seed time by a random percentage based on their team’s performance history. This simulates a taper
  3. Re rank each event based on the modified times and score out the meet
  4. Repeat 10,000 times

The first scenario I tried was assuming each team’s taper will look like it did last year.  I got the taper numbers from Swimulator’s taper tab which shows how each team’s times improved from this point in the season to the end of the year. Last year, ACC women’s teams improved by the following margins vs their top times as of this point in the season:

2017 Taper
Virginia 0.7%
Louisville 1.6%
North Carolina 2.20%
Notre Dame 0.88%
Duke 0.7%
NC State 2.80%
Florida State 0.52%
Virginia Tech 1.3%
Georgia Tech 1.3%
Pittsburgh 0.45%
Miami 0.81%
Boston College 0.25%

Using those tapers with a standard deviation of 1.8% (pretty standard for D1 teams) we get the following place probability chart (again this does not include diving). Each number represents percentage of simulations each team finished in each place. The 0%s represent that it happened in the sim, but less than .5% of the time. The blanks mean it never happened.:

1st 2nd 3rd 4th 5th 6th 7th 8th 9th 10th 11th 12th
Louisville 74% 26% 0%
NC State 26% 74% 0%
North Carolina 0% 95% 5% 0%
Virginia 5% 93% 3% 0%
Virginia Tech 0% 2% 74% 20% 3% 0% 0%
Notre Dame 0% 20% 58% 18% 3% 1% 0%
Duke 3% 19% 59% 15% 5% 0%
Florida State 0% 1% 11% 45% 39% 4%
Georgia Tech 0% 1% 10% 36% 46% 8%
Pittsburgh 0% 1% 10% 88% 0%
Miami 100% 0%
Boston College 100%

This model picks Louisville as the favorite to win the swimming portion of the meet, but gives NC State a puncher’s chance of an upset. North Carolina and Virginia are pretty locked into the next two spots. However, this assumes that last year’s tapers were a reasonably good predictor of this year’s drops. Team drops are correlated one year to the next, but they aren’t exactly the same every year. Before we can trust these predictions, we need to know how sensitive the predictions are to changes in team’s taper patterns. First, let’s try a couple small changes.

NC State is typically a big taper team, but last year was especially big. Virginia is typically an average taper team, but their new coach used to be on NC State’s staff. It’s reasonable to assume NC State’s taper will be a bit smaller (regression to the mean) and Virginia’s will be a bit bigger this year (new coach, new philosophy). To see what this scenario looks like, I tweaked NC State’s taper down to a more reasonable 2.3% and tweaked Virginia’s up to 1%. This produced the probabilities in the table below.

Louisville becomes an even stronger favorite. Virginia and North Carolina get closer, but North Carolina remains favored for 3rd. Both North Carolina and Virgina have strong diving contingents. Last year North Carolina scored 115 diving points to Virginia’s 111. Neither team graduated any key divers, so diving doesn’t look like a decisive advantage for either team. This scenario still assumes a larger taper for North Carolina than for Virginia. Despite Virginia’s coaching change I think this is reasonable. UNC has a history of big tapers (for example: 2015). Virginia’s mid season taper, by all indications, was pretty substantial. They have two relays currently ranked in the top 3 in the country and several of their returning swimmers are ranked as well or better than they were ranked at the end of last season (ex. Marrkand projects to 15 points at nationals right around her mark from last year, Cooper projects to 14 after not scoring last year).

1st 2nd 3rd 4th 5th 6th 7th 8th 9th 10th 11th 12th
Louisville 98% 2% 0%
NC State 2% 84% 12% 1%
North Carolina 0% 12% 67% 21% 0%
Virginia 2% 20% 78% 0%
Virginia Tech 0% 76% 20% 3% 0% 0%
Notre Dame 0% 20% 58% 17% 3% 1% 0%
Duke 2% 19% 59% 15% 5% 0%
Georgia Tech 2% 10% 35% 46% 8%
Florida State 0% 1% 11% 44% 39% 4%
Pittsburgh 0% 2% 10% 88% 0% 0%
Miami 0% 100% 0%
Boston College 0% 100%

Next I tried a split the difference approach. I ran a model with each team’s taper number set at the half way point between last year’s taper and the conference average of 1.1%. This accounts for team specific taper patterns while throwing out some of the single year variability of only using one year as a data point by regressing to the mean. The downside to this method is that it might underrate team specific taper training patterns. Despite that, of all the methods in this article, I like this one the best.

1st 2nd 3rd 4th 5th 6th 7th 8th 9th 10th 11th 12th
Louisville 99% 1% 0%
NC State 1% 86% 11% 2% 0%
Virginia 0% 9% 54% 36% 0% 0%
North Carolina 4% 34% 61% 1% 0%
Virginia Tech 0% 0% 54% 32% 11% 2% 0%
Notre Dame 0% 0% 36% 41% 19% 4% 0% 0%
Duke 0% 8% 24% 52% 15% 2% 0%
Florida State 1% 3% 16% 61% 17% 2%
Georgia Tech 0% 0% 2% 16% 56% 25% 0%
Pittsburgh 0% 3% 25% 72% 0%
Miami 0% 100% 0%
Boston College 0% 100%

Another approach is to throw out history and say everyone’s taper baseline is the same. With everyone’s taper set to the conference average, we get the below probabilities. Suddenly Virginia becomes favored for 2nd. They also have a diving advantage over Louisville which would give an outside, but not impossible chance to win. Another interesting note here is that, despite being ahead of Virginia Tech on the psych sheet, Duke is ranked behind them in this sim with a neutralized taper factor.

1st 2nd 3rd 4th 5th 6th 7th 8th 9th 10th 11th 12th
Louisville 99% 1%
Virginia 1% 93% 6% 0%
NC State 5% 70% 21% 3% 0% 0%
North Carolina 1% 22% 60% 13% 3% 1% 0%
Notre Dame 0% 2% 11% 41% 26% 15% 5% 0%
Virginia Tech 0% 5% 26% 34% 24% 9% 0%
Duke 0% 1% 14% 28% 39% 17% 1% 0%
Florida State 0% 2% 8% 21% 62% 6% 1%
Pittsburgh 0% 0% 4% 53% 43%
Georgia Tech 0% 0% 3% 39% 57%
Miami 100% 0%
Boston College 0% 100%

In Summation

Based on your expectations of how teams will taper, some expectations about how the meet will play out should change, but some should remain constant. Louisville is always the favorite. It would require pretty unreasonable assumptions to say other wise. Virginia, NC State, and North Carolina are the next three in some order depending on how you expect times to evolve. Miami and Boston College are the bottom 2.

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Swimmom
6 years ago

Here Come the IRISH!!!???

v/r
6 years ago

Does this analysis include Kylie Perry for nc state since she probably won’t be swimming? If so that probably drops them down to third or fourth.

2 Cents
6 years ago

2 Thoughts… and as a Math major I love the numbers and stats to back up everything you said.

1) UVA does have a new coach and taking into account last year’s taper might not be as accurate for them given the major change in coaching and coaching philosophy they have experienced this year. Along those same lines, do your total taper times go through NCAAs last year or just until ACCs? I feel like with it being NCAAs that will throw a lot of that percentage off, since some teams will focus more on NCAAs (Louisville, UVA) than ACCs.

2) I would throw out the taper adjustment that came from the 1650 and 500 because those will skew… Read more »

YAS
Reply to  2 Cents
6 years ago

wow wow wow. love this article love the comment. love when swimmers get super numbers nerdy

Andrew Mering
Reply to  2 Cents
6 years ago

I always appreciate the discussion. Here’s a very long winded reply

1)The coaching change is a valid point (that I did mention in the article). That is one of the main reasons why I showed the model outcome with so many combinations of variables. I wanted to show how things changed when your baseline expectations change. The new coaching staff is a major thing that changes expectations and I’m not sure exactly what to expect out of VIrginia. I defend using old taper data (which is obviously not perfect) with a couple points: First, a taper being correlated year to year is partly on coaching philosophy and partly on the fact that many of the same athletes are involved one… Read more »

Bob
6 years ago

Here’s the problem with your predictions. UVA had NO mid season taper. UVA blew Louisville, NC and UNC out of their pool. UVA takes it. See you in Greensboro.

Top trait
6 years ago

This is an AWESOME analysis! Thank you! If I weren’t already happily married to my dream man, the ability to do a number analysis on a conference meet like this would be at the top of my list of important traits to marry! ?

Swimmer
6 years ago

Key injuries will definitely hurt NC State this year. Great analysis and nice predictions but the ladies still have to show up and swim. Louisville may not be in a full taper with NCAAs right around the corner. Louisville takes it. UVA will make it interesting.

FREEBEE
6 years ago

The analysis is spot on but I think the surprise will be UVA at ACC and/or NCAA

Joel Lin
6 years ago

UVA takes it.

About Braden Keith

Braden Keith

Braden Keith is the Editor-in-Chief and a co-founder/co-owner of SwimSwam.com. He first got his feet wet by building The Swimmers' Circle beginning in January 2010, and now comes to SwimSwam to use that experience and help build a new leader in the sport of swimming. Aside from his life on the InterWet, …

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