Sports Analytics Glossary
Your comprehensive guide to sports analytics terms, metrics, and abbreviations
1st Serve % (1st Serve %)
The percentage of first serves that land in the service box. A higher percentage indicates better serve consistency and reduces pressure on the second serve.
2nd Serve % (2nd Serve %)
The percentage of second serves that land in the service box. This metric is crucial as it directly relates to double fault frequency.
Ace
A serve that is not touched by the receiver, resulting in an immediate point for the server. Aces are typically achieved through high serve speed or exceptional placement.
Advantage (Ad)
The point after deuce when one player leads. If the player with advantage wins the next point, they win the game; if they lose, the score returns to deuce.
Approach Shot
A groundstroke hit while moving forward toward the net, typically used to transition from baseline to net play. Approach shots should be deep and force defensive replies.
ATP Points (ATP)
Association of Tennis Professionals ranking points awarded based on tournament performance. ATP points determine world rankings for male professional players.
Baseline Rally
An exchange of groundstrokes where both players remain behind the baseline. Modern tennis is dominated by baseline rallies featuring heavy topspin and powerful shots.
Block Return
A defensive return where the racket is simply held firm to deflect a powerful serve back into play. Common against serves exceeding 120 mph.
Break Back
When a player immediately breaks their opponent's serve after having their own serve broken. Breaking back restores parity in the set.
Break of Serve
When the receiving player wins a game in which their opponent was serving. Breaking serve is crucial for winning sets and matches.
Break Point
A point that, if won by the receiver, results in breaking the server's serve. Break points occur when the score is 30-40, 0-40, 15-40, or at advantage receiver.
Break Point Conversion
The percentage of break point opportunities that are successfully converted into breaks of serve. Elite players typically convert 40-50% of break points.
Chip Return
A shortened, sliced return shot often used against powerful serves. The chip return keeps the ball low and gives the returner time to recover position.
Deuce
A score of 40-40 in a game. From deuce, a player must win two consecutive points (advantage, then game point) to win the game.
Double Fault
When a player fails to land both their first and second serve in the service box, resulting in the loss of a point. Double faults are critical errors in tennis.
Drop Shot
A softly hit shot that barely clears the net and lands short in the opponent's court. Drop shots are tactical weapons used to move opponents forward or win points outright.
Fault
A serve that fails to land in the correct service box or violates serving rules. Players are allowed two attempts per point, with a second fault resulting in a double fault.
Forced Error (FE)
An error caused by an opponent's aggressive or well-placed shot that forced the player into a difficult position. Distinguished from unforced errors in post-match analysis.
Grand Slam
The four most prestigious tournaments in professional tennis: Australian Open, French Open, Wimbledon, and US Open. Winning all four in a calendar year is the sport's ultimate achievement.
Kick Serve
A type of spin serve that bounces high and kicks away from the receiver, typically using topspin. Often used as a second serve due to its high margin of error and difficulty to attack.
Let Serve
A serve that touches the net but still lands in the correct service box. The serve is replayed without penalty to the server.
Lob
A high, arcing shot designed to go over an opponent at the net. Lobs can be offensive (topspin lob) or defensive (defensive lob to buy time).
Match Point
A point that, if won, will result in victory for the leading player. Match points represent the most pressure-filled moments in competitive tennis.
Net Points
Points played when a player approaches the net to finish with a volley or overhead. Net point success rate indicates touch and tactical effectiveness.
Passing Shot
A groundstroke hit past an opponent who is at the net. Effective passing shots require precision, power, and tactical awareness of court positioning.
Rally Length
The number of shots in a point exchange. Rally length varies significantly by court surface, with clay courts typically producing longer rallies than grass courts.
Return Ace
A return of serve that is not touched by the server, immediately winning the point for the returner. Also known as a winner off the return.
Return Game
A game in which a player is receiving serve. Success in return games, particularly converting break point opportunities, is essential for winning matches.
Return Points Won
The percentage of points won when returning serve. This is a key performance indicator measuring a player's ability to break serve and create pressure on opponents.
Return Position
The location where a player stands to receive serve. Positioning varies based on serve speed, spin, and tactical preferences, typically several feet behind the baseline.
Serve and Volley
A tactical approach where the server immediately rushes to the net after serving to finish the point with a volley. Once dominant, this style is now less common in modern tennis.
Serve Speed
The velocity at which the ball travels during a serve, typically measured in miles per hour (mph) or kilometers per hour (km/h). Elite players can exceed 140 mph on first serves.
Service Box
The rectangular area diagonally opposite the server into which a serve must land. The box is bounded by the net, center service line, service line, and singles sideline.
Service Game
A game in which a player is serving. Holding serve (winning your service game) is fundamental to success in tennis.
Service Winner
A serve that is touched by the opponent but not returned into play. While not an ace, it still results in an immediate point for the server.
Set Point
A point that, if won, will result in winning the current set. Set points are critical junctures that can determine match momentum and outcome.
Tiebreak
A special game played when a set reaches 6-6 (or specified score). The first player to reach 7 points with a 2-point margin wins the tiebreak and the set.
Unforced Error (UE)
A mistake made when a player had time and position to make a successful shot but failed to do so. Minimizing unforced errors is crucial for consistent performance.
Winner
A shot that is not touched by the opponent and wins the point outright. Winners demonstrate offensive capability and shot-making quality.
WTA Points (WTA)
Women's Tennis Association ranking points awarded based on tournament performance. WTA points determine world rankings for female professional players.
Quick Reference
Common sports analytics metrics you should know
Baseball Metrics
- WAR - Wins Above Replacement
- wOBA - Weighted On-Base Average
- FIP - Fielding Independent Pitching
- wRC+ - Weighted Runs Created Plus
Soccer Metrics
- xG - Expected Goals
- xA - Expected Assists
- PPDA - Passes Per Defensive Action
- PSxG - Post-Shot Expected Goals
Basketball Metrics
- PER - Player Efficiency Rating
- TS% - True Shooting Percentage
- BPM - Box Plus/Minus
- VORP - Value Over Replacement Player
Football Metrics
- EPA - Expected Points Added
- CPOE - Completion Percentage Over Expected
- DVOA - Defense-adjusted Value Over Average
- PFF Grade - Pro Football Focus Grade