AI Volleyball Stats Explained: What Coaches Need to Know

Core Stats Every Coach Should Understand

These are key concepts every coach should understand and apply when analyzing performance.

Note: These statistics can be interpreted as individual or team stats.

Basic Skills & Statistics

Attack

• Kill: An attack that is not returnable by the opposing team and leads directly to a point for the attacking team.
• Error: Charged to a player whenever an attack or attacker: hits the ball out of bounds; hits the ball into the net, resulting in a four-hit violation; or is blocked down by the opposition to the same side as the attacker, and cannot be kept in play as a direct result of the block. This directly results in the defending team winning the point.
• Total attempts: When a player attempts to attack the ball into the opponent's court. The ball may be set, tipped or hit as an overhead contact. There are three possible outcomes of an attack attempt: kill, error or attempt (an attack not resulting in a kill or an error).
• Attack percentage: The equation used is (kills - errors)/total attempts. For example, 5 kills minus 3 errors, divided by 10 total attempts equals .200 attack percentage.

Serve

• Service ace: When a player serves the ball and the opposing team is unable to pass it. An ace occurs when the ball either hits the ground or is shanked off of a passer, making a second touch impossible.
• Service error: Charged to a player if: the serve hits or fails to go over the net; the serve goes out-of-bounds; the server is called for a foot or time violation; or the server serves out of rotation.
• Total attempts: A service attempt is given any time a player attempts to serve the ball, including when a player is given a service ace or service error.
• Serving percentage: The equation used is  (service aces – service errors) / total attempts. For example, 4 aces minus two errors divided by 15 total attempts equals .133 serving percentage.

Serve Receive 

• Pass quality rating (0-3):
  • 3 point pass: A "perfect" pass or a pass where a setter can comfortably set all three attackers.
  • 2 point pass: A "medium" pass or a pass where a setter can comfortably set two attackers. Typically a 2-rated pass would not be easy to set your middle attacker.
  • 1 point pass: A "poor" pass. Typically a setter only has one option on who to set and possibly no options. This is a pass that does not immediately result in an error, but the setter is not able to choose who to set.
  • 0 point pass: A “zero” pass results in an ace for the other team.
• Total attempts: Culmination of all pass attempts.
• Passer percentage: Sum of all the pass quality ratings divided by the total attempts.

Set

• Assist: Any contact, typically a set, where the next immediate contact results in a kill.
• Total attempts: Anytime a set, pass or dig to a player results in that teammate attacking the ball.

Dig 

• Dig: Awarded when a player successfully plays a ball that has been determined to be an attack attempt by the opponent.
• Cover: A cover is also counted as a dig. A cover is the result of playing the ball up immediately after a block occurs.

Block 

• Block: Awarded when a player (or players) at the net deflect(s) an opponent’s attack and the ball lands on the attacking team’s side for a point or an immediate sideout, without any other player making a play on the ball.
• Block assist: Any successful block resulting in an immediate point where there’s more than one front row player with their hands above the net at the point of the attacker's contact with the ball.
• Block solo: Any successful block resulting in an immediate point where there’s only one front row player with their hands above the net at the point of the attacker's contact.
• Block error: Number of blocks where the player was called for fault, such as touching the net or crossing the center line.
• Blocks per set: The average number of successful blocks a player or team records per set. It’s calculated by dividing the total number of blocks by the total number of sets played.

Serve and Reception Effectiveness

Serving and passing are the foundation of successful volleyball, and the ability to interpret these stats with clarity can make a major impact on how coaches train, adjust and win. 

Serving

• Point scoring: Refers to the total number of points a team earns while they’re serving, including aces and any plays that result in winning the rally during their service.
• Ace percentage: The ratio of aces to total serves, showing how often a player or team scores directly from their serve.
• Error percentage: The ratio of service errors to total serves, showing how often a player or team makes a mistake while serving.
• Ace to error ratio: Measures a player's serving effectiveness by comparing the number of aces they make to the number of service errors they commit.

Passing

• Pass rating: Receptions are judged on a three or four-point scale (0 being worst and 3 or 4 being best).
• Perfect pass percentage: Number or receptions that are considered perfect.
• Good pass percentage: Number of receptions that are considered perfect or good (2 pass).
• Error percentage: Number of reception errors.

Understanding these metrics allows coaches to make data-backed decisions about serving strategies and passing formations.

Siding Out vs. Transition Analysis

Understanding the difference between sideout offense and transition offense is crucial to evaluating a team’s efficiency. These phases require different strategies, tempos and decision-making—so tracking performance separately gives coaches a clearer path to improvement.

Offense (Sideout Focus)

• Side out percentage: The rate at which a team successfully wins the point during rallies where they are siding out.
• First ball kill: Refers to when a team scores a point on their very first attack after serve receive.
• Attack distribution based on pass quality: Analyzes how a team varies its set choices depending on the quality of the pass.

Defense (Transition Focus)

• First ball dig to transition kill percentage: Measures how often a team successfully scores a point on the first attack immediately following the first defensive dig.
• Transition attacking efficiency: The attack percentage for an athlete or team when removing their first ball side out attacks.

In-System vs. Out-of-System Analysis

Recognizing whether a team is operating in-system or out-of-system will make identifying the quality of their offensive opportunities easier. In-system plays typically allow for faster tempos and more attacking options, while out-of-system situations demand adjustments and often limit choices. Tracking these scenarios separately reveals how well a team performs in certain situations.

Note: Kill percentage and error percentage are often evaluated in these skills as well— definitions are listed above in Basic Skill section.

In-System Offense

• Attacking efficiency based on perfect pass: Player or team attacking efficiency based on a perfect pass.

Medium-Pass Offense

• Attacking efficiency based on medium pass: Player attacking efficiency based on a medium pass. 

Out-of-System Offense

• Attacking efficiency based on poor pass: Player attacking efficiency based in a medium or poor pass.