Sideout %: What Is It Good For?

Let's go one step beyond, "sideout more."

For the past several months, I’ve been fleshing out the analytics framework I call the Triangle. If you need to get caught up, here’s the 4 main articles that outline the concept of the Triangle, as well as the 3 points of the Triangle.

• The Triangle

• Terminal Serving

• First Ball

• Transition

I also described what I call Team Profiles, which are 7 different ways that teams might express strength or weakness in those areas of the Triangle. The last post in this series, Balanced, also contains links to the other posts in that series.

Today starts a long dive into the next level of analysis, which I’ll eventually call Key Factors. But before we get there, I want to look at arguably the simplest statistic in volleyball and show how we can actually get some valuable diagnostic information from it.

Sideout %

Sideout % is a really important statistic, but you can barely even call it that, because it’s so simple. Sideout % means: how often did I win the point when the other team served? So if you look at something like “Sideout Differential,” what you’re really just saying is, “Point Differential.”

It’s really important that we sideout better than the other team.

Yes scoring more points is the objective in a game of sports-ball.

Jokes aside, if Sideout % is so simple, why do we use it so much? Well first, simple metrics are usually good ones. Additionally, a lot of coaches have an understanding (whether they express it as I’m about to, or they have just developed this as intuition) that they are also comparing Sideout % to their current Win-Loss record and to what a typical Sideout % is at the level they are coaching. And that’s what we’re interested in here.

Sideout And Opponent Sideout

If you know your Sideout, and you know your Opponent’s Sideout, you know your point differential, which means that you also know a pretty good approximation of your win-loss record.

Sideout - Opponent Sideout = Sideout Differential = Point Differential = Wins and Losses

So now we have a two-factor equation. And this is a reason that experienced coaches can simply use Sideout as a one-stat-to-rule-them-all. Because (I hope) you know your win-loss record, if you also know Sideout, then you have a pretty good idea what your Opponent Sideout might be - lower if you’re winning and higher if you’re losing.

But let’s put some more precise points on it by adding one additional factor.

Compare To The Median

Knowing your Sideout and Opponent Sideout is valuable, and when you add in knowledge of your level (aka what the median sideout at your level is), then you have a powerful diagnostic tool for planning training. If your Sideout is strong (relative to your level) and your ability to prevent Opponent Sideout is relatively weaker, then you have an Offensive Strength team. If your ability to prevent Opponent Sideout is strong (relative to your level) and your ability to Sideout is relatively weaker, then you have a Defensive Strength team.

For example, take two teams in different leagues that both have a +4% Point Differential, which also means that they have a +4% Sideout Differential¹. Now imagine that these differentials are accomplished in two different ways:

Team A: 58.7% Sideout, 56% Opponent Sideout

Team B: 61% Sideout, 58.7% Opponent Sideout

These are two pretty different teams. Team A is almost exactly average in Sideout and above-average in Opponent Sideout. Team B is almost exactly average in Opponent Sideout, and above-average in Sideout.

These are real examples, because Team A is 2021 Michigan and Team B is 2021 Ole Miss.² They finished with nearly identical records: Michigan at 11-9 in the Big 10 and Ole Miss at 10-8 in the SEC. But they got there in different ways that have implications for us as coaches.

We’ll call Michigan a Defensive Strength team and Ole Miss an Offensive Strength team. We’ve touched on this in previous Team Profile posts

First Ball Data Dump

but we’ll go deeper into this idea now, starting with Offensive Strength teams.

The Numbers

A few details here:

SO and oSO are Sideout and Opponent Sideout respectively.

SO Index and oSO Index are how many standard deviations from the mean that the team was. So Texas’ 70.7% Sideout was 2.6 standard deviations above the mean in the 2021 season.

And SO Ratio, as you might be able to tell, is simply the difference between the SO and oSO indices.

This is a list of the top-10 teams in SO Index, which, to be clear, is not the top-10 sideout teams. It is the top 10 teams in the measure of, “their success was probably more due to sideout ability than the ability to prevent opponent sideouts.”

As has been the case with many of these Team Profile exercises, there is a wide range of team success. There are some very successful teams in this top 10, as well as some teams that didn’t win much. And indeed, the correlation between SO Index and Win % is essentially 0.³

So what’s the point of this measure? To understand your team better. The choice to fix your weaknesses or enhance your strengths is a more difficult decision. I’ve touched on that in some previous posts. But in order to make that decision, it would be good to know what your strengths and weaknesses actually are.

We’ll explore this concept related to Offensive Strength or Defensive Strength in future posts, but I’ll leave it there for now.

1. Technically this diverges slightly in very high sideout or very low sideout environments. But since the vast majority of volleyball is played in sideout environments between 35 and 65%, we can basically treat PD and SD as the same.

2. With some slight rounding to make the examples simpler to compare.

3. Which, to remind, doesn’t mean that it’s bad to have a high (or low) SO Index. It just means that you could be successful (or unsuccessful) with a high SO Index, low SO Index, or anywhere in between.