How to Measure Attacking Performance

tl:dr

• The volleyball attack is hugely important because it helps you win matches

• An attack attempt is an attempt to attack (hit strategically) the ball into the opponent’s court in an effort to win a point. It has three broad outcomes: point won (kill), point lost (attack error), and the continuation of play (zero attack)

• There are three common ways to measure the attack: Kills Per Set, Kill % and Hitting %. I would say the Hitting % [=(Kills – Attack Errors)/ Total Attack Attempts) is the gold standard to measure the attack

The Importance of the Attack

The volleyball attack is the most important technical skill critical to winning in volleyball (see link and link). The two charts below (in a slideshow) show the difference between a winning and losing team’s Hitting % [= (Kills – Attack Errors)/ Total Attack Attempts] versus the difference in set scores, e.g. a set score of 25-23 has a difference of 2 points. You can see the bigger the difference, the bigger the set score difference. That is, the better you attack, the easier it is to win the set. I found the same effect in both the men’s and women’s games.

This makes sense. If you think about it, to win tournaments, cups, or leagues, you need to win matches.  To win a match, you have to win three sets.  To win a set, you have to score 25 points before your opponent does.  Since around 70% of points are won and 50% are lost via the attack (see the slideshow below), it makes sense that attacking is critical to winning in volleyball.

So what is the best way to measure attacking performance?

Defining the Raw Attack Data

Before we can measure attacking performance, we should explain what the raw attack data means. An attack attempt is an attempt to attack (hit strategically) the ball into the opponent’s court in an effort to win a point.  If the action is only intended to keep the ball in play then this is usually considered a free ball attempt and not an attack attempt. An attack attempt has three broad outcomes: point won (kill), point lost (attack error), or the continuation of play (zero attack). You normally include attacks stuffed (where the blocker stuffs the attack for a point won) as an attack error but you can make the argument that it shouldn’t (see link to read more).

Attack Performance Indicators

A performance indicator in sports is a selection or combination of performance variables that describe some or all aspects of sports performance. This is so it creates a level playing field so we can understand and compare the different levels of performance whether it’s between opponents, previous performances, or peer group performance. There should be some form of calculation to normalise the raw performance data into averages, percentages, ratios, or differentials.

So what are the common performance indicators used to measure attacking performance.

Kills/ Attack Errors Per Set Average

Kills Per Set = Total Kills/ Sets PlayedAttack Errors Per Set = Total Attack Errors/ Sets Played

The Kills Per Set is the average number of attack kills per set. The Attack Errors Per Set is the average number of attack errors per set. A 5.00 kill and attack error per set average is considered very good and bad, respectively.

The advantage of using this performance indicator is it is easy to understand for players and coaches and it is commonly used.  

The disadvantage of using this performance indicator is it doesn’t normalise the data properly because it doesn’t take into account the total attack attempts. A player with many attack attempts, like outside hitters, may have a high kills per set average, while effective attackers with fewer attempts, like middle players, will not. Click on this link to read further why I don’t really like Per Set Averages.

Kill/ Attack Error %

Kills % = Total Kills/ Total Attack AttemptsAttack Error % = Total Attack Errors / Total Attack Attempts

A Kill % is the percentage of attack attempts that result in a kill (point won). An Attack Error % is the percentage of attack attempts that result in an attack error (point lost). If you have a player with a 50+% kill %, they tend to be your monster attackers.

The advantage of using this performance indicator is it is easy to understand for players and coaches and it is commonly used.  It also takes total attempts into account which the per set average did not.

The disadvantage of using this performance indicator is doesn’t consider both kills and errors. A 40% kill rate is impressive, but if paired with a 50% attack error rate, the player is losing more points than they score, which is ultimately hurting the team’s chances of winning.

Hitting %

Hitting % = (Total Kills - Attack Errors)/ Total Attack Attempts

A Hitting % is the percentage of total attack attempts that result in net kills since every attack error cancels out a kill. To put it another way, it is the difference between a Kill % and an Attack Error %. If a player has a 30+% and 40+% hitting % for outside hitters and middles, respectively, then they tend to be your best attackers. Of course, it depends on the team’s level of play.

The big advantage of this performance indicator is it takes into consideration both point-scoring and point-losing actions. You can see if a player is hurting or helping the team’s chances of winning. Perhaps the most important thing is the Hitting % is also highly correlated to winning in volleyball. It means the team with the higher Hitting % tends to win the match.

The disadvantage of this performance indicator is it ignores all other actions that are not kills or attack errors. These zero attacks should be worth something. For example, an attack attempt that results in the defence shanking the ball and chasing it down should be worth more than a soft roll shot that the defence can dig perfectly but the Hitting % considers them the same.

Advanced Performance Indicators

There are some advanced performance indicators that measure attacking performance. The Attack + Rally Win % considers the rally outcome of the zero attacks. The Hitting % Over Expected looks to normalise the attacking conditions, e.g. by the quality of the first ball. However, they do require a lot of work, data, and a computerised system to calculate this so it’s not something a regular team can adopt. They also deserve a blog post on their own and will be something I will write soon (***Update 24 February 2025 | I did write it. Click on this link).

Final Thoughts

I would not even bother with the Kills Per Set average. It’s a terrible performance indicator. Again, read here why I don’t like it.

The Kill % is ok to refer to if you want to know who your potential monster attackers can be. If you had a player with a low Hitting % of 10% but a high Kill % of 40%, then there’s huge potential if you can work on minimalising the player’s errors and getting it close to a 40% Hitting %. Conversely, if you had a player with a 10% Hitting % and a 20% Kill %, then your ceiling is around 20% Hitting %. You can try and improve their Kill rate but that’s a lot harder to do compared to minimalising errors. However, you probably know who your monster attackers are just by seeing how much power they have.

I would say the Hitting % is still the gold standard to measure attacking performance. It considers total attempts, kills, and errors, which the other two performance indicators do not. The Hitting % is also highly correlated to winning volleyball matches. This means you can confidently work on improving this number and this should correspond to winning more matches. That’s what I do anyway.