COVID Brings Out the Sun for Stormy Petrels Women’s Volleyball

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The past year has been strange for sports at all levels. Shortened seasons, cancelled games, and a surplus of “Out (COVID)” on injury reports. It felt like everyone, from the NBA to your local rec league, just barely got through their seasons. This disruption produced some unlikely outcomes, one of which I’d like to explore here.

I went to my first Oglethorpe women’s volleyball game on September 2, 2017. The Petrel’s were taking on Illinois Tech in the second game of the 2017 Stormy Petrel Challenge. They fell to an early 0-2 deficit, and the third set seemed lost when they found themselves down 17-22. Jacoby Sims scored three quick kills to force an Illinois timeout at 20-22, and the Petrels rallied to a 26-24 victory. They won the next two sets by 5 and 3 points, respectively, completing the 3-2 comeback. The game was fast, explosive, and tense. I was hooked. I couldn’t wait to see the rest of the season.

After the Illinois Tech game, the Petrels went on a 13 game losing streak. They ended the season 4-21 overall, and 2-12 in conference play. Needless to say, that first game set my expectations a little too high.

You see, the Stormy Petrels are a terrible women’s volleyball team. I mean atrocious. They have not had a winning season in the past ten years. In those ten years, they went 16-127 in conference play, and never won more than 3 conference games in a single season. Whether we bring in new coaches, new players, or new staff, it’s always the same. The Petrels are the bottom of the barrel of the Southern Athletic Association, and they have been for a long time.

And yet, I just can’t quit them. Even though they’re awful, even though no one goes to the games, and even though I don’t even live in Georgia anymore, I still hold out hope that maybe, just maybe, this is the year they turn it around. Well, finally, this year came to pass, and the Stormy Petrels were not a complete joke.

Season Oglethorpe Conference record
2020-2021 6-5
2019-2020 0-16
2018-2019 2-12
2017-2018 2-12
2016-2017 3-11
2015-2016 0-14
2014-2015 3-11
2013-2014 0-14
2012-2013 2-12
2011-2012 3-11
2010-2011 1-14

In a shortened, conference-only season, second-year coach Anna Braun led the Stormy Petrels to a 6-5 finish. You may look at that and say, “Robert, that’s only 55%. It took a shortened season, a COVID-depleted conference, and over ten years years to barely win half of their games?” And while, yes, you would be correct, this is the Petrel’s best percentage, first winning season, and best conference ranking since joining the SAA. For Oglethorpe, 6-5 is as good as winning the title.

To explain how amazing this is, I want to provide some context. First we need to take a detour into the world of analytics.

Introducing: Elo

Elo is a numerical system used to rate the strength of teams. Arpad Elo first introduced it to rank the strength of chess players, but it is easily adaptable to any head-to-head competition. Here’s how it works.

An “average” team has an Elo score of 1500. Stronger teams have higher scores, and weaker teams have lower scores. Your score increases if you win a game, and decreases if you lose a game. Two teams with equal scores have even odds of winning, having a score of 70 points higher gives you about a 60% chance of winning, and having a score of 150 points higher gives you about a 70% chance of winning.

Elo difference Win probability for stronger team
0 50%
75 60.5%
150 70%
300 85%
600 97%

Like I said, you get a higher Elo score by winning games, and a lower score by losing games. How much your score changes depends on the following ideas:

  1. A strong team beating a weak team gets a small score bump. (We expect strong teams to beat weak teams.)

  2. A strong team beating a strong team gets a moderate score bump. (We learn about the strong teams, but not their relation to a third, weaker team.)

  3. A weak team beating a strong team gets a big score bump. (This is the most surprising situation.)

The “base change” is 40 Elo points. That’s the most you could increase or decrease after a game. You get a proportion of that that depends on your odds of winning or losing the game. If you win, then you get 40 times the probability that you would lose. If you lose, then you lose 40 times the probability that you would win. For the other side, Elo is a zero-sum game: The loser’s score goes down the exact amount the winner’s goes up.

Let’s see some examples.

If an average team (Elo 1500) met another average team (Elo 1500), we’d predict that both teams have a 50% chance to win. The winner had a 50% of losing, so they would get 20 points (Elo 1520) and the loser would fall 20 points (Elo 1480).

If an average team (Elo 1500) met an above average team (Elo 1600), we’d predict that the above average team has about a 64% chance to win. If the stronger team won, then they would only get 36% of 40, or 14 points (Elo 1614), while the average team would only fall 14 points (Elo 1496). If, on the other hand, the average team won, then they would get 64% of 40, or 26 points (Elo 1526), while the stronger team would fall 26 points (Elo 1574).

With this description of Elo out of the way, let’s see the history of the SAA in a graph.

Elo scores

Using data compiled from the 2012-2013 season to the 2019-2020 season, I have computed the Elo scores of every women’s volleyball team in the SAA and plotted them above. (I left out Sewanee because they didn’t play in the 2020-2021 season.) The graph shows a clear divide into three groups:

  1. The pack leaders, Berry, Birmingham-Southern, and Hendrix. These teams have always been at least average, and have been moderately to very strong in recent years.

  2. The middling runts, Rhodes, Centre, and Millsaps. These teams were decent a while ago, but have been in a sharp decline recently. They are firmly below average.

  3. The Stormy Petrels, the dregs of the SAA.

Now that we have some context for how bad the Stormy Petrels are, 6-5 doesn’t sound so bad, does it? How does Oglethorpe’s Elo look after this miraculous winning season?

Elo redux

Wow! Oglethorpe’s Elo skyrocketed after this barely-winning year. The wins came from Centre (x2), Hendrix, Rhodes, and Millsaps (x2). The losses came from Birmingham-Southern (x3), Rhodes, and Hendrix. Except for Rhodes, which nearly cancels out, the losses were to teams so overpowered they barely lowered Oglethorpe’s rating. The wins, since Oglethorpe had such a meagre rating, produced much more.

A postseason shocker: simulating with Elo

The real shocker is that 6-4 was enough to put the Stormy Petrels into the SAA playoffs with their first top-4 finish ever. (Only the top-4 teams played this year.) We can quantify how surprising this was by simulating the 2020-2021 season.

Once we know the Elo score of two teams, we can simulate a matchup between them by flipping a biased coin. If Elo says the stronger team has a 75% chance to win, then we flip a coin that comes up heads 75% of the time, and tails 25% of the time. If we see heads, then the stronger team “won,” and otherwise they “lost.” Proceeding in this way, we can simulate an entire season of games as long as we know the Elo scores of the teams involved to a sufficiently high accuracy.

So, I did that. I simulated the 2020-2021 season 10,000 times and figured out how likely it was that each team made the playoffs. Oglethorpe had around a 20% chance, which is probably their best chance at finishing top-4 in a long time. The three top-dogs (Berry, Birmingham-Southern, Hendrix) all made the playoffs, so Oglethorpe had to leap over the middle-of-the-pack teams (Centre, Rhodes, Millsaps) to get fourth place.

Team Probability of top-4 SAA finish (bold = actual)
Berry 97.92%
Birmingham-Southern 96.78%
Hendrix 85.73%
Millsaps 53.29%
Centre 26.08%
Rhodes 21.09%
Oglethorpe 19.11%

A 20% event happens, on average, once every five times, so it isn’t so crazy that Oglethorpe would make the top-4. Of course, going any further than the first round would probably require beating a big-dog team, and accordingly the probability that Oglethorpe would win the SAA title was exceedingly small.

Team Probability of winning SAA title (bold = actual)
Berry 38.73%
Birmingham-Southern 34.09%
Hendrix 18.22%
Millsaps 4.17%
Centre 2.72%
Rhodes 1.31%
Oglethorpe 0.76%

What’s next for the Stormy Petrels?

Hot off their highest finish in a decade, where do the Stormy Petrels go? Will the new coach lead us to glory? Will she crash and burn how all the rest have? We don’t know for sure, but all the machinery I’ve laid out here will enable us to make predictions about the next season. As soon as the schedule is released I’ll be churning those out.

My mind tells me that the likeliest outcome is for Oglethorpe to have a terrible year, like we always do. My heart tells me that we’re going to win it all, baby.