The 3 Commonly Used Tennis Metrics that Don't Help Player Development and Why

Rankings. Ratings. Match statistics. Video. Dashboards. Big data. AI. Everything can now, apparently, be measured. Tennis has never had more information available to players, parents and coaches.

Here's the question: are the measurements that are being used actually helping develop players?

Measurement matters, but only when it helps players, coaches and parents understand what is actually happening in matches, why it is happening, and what should be developed next.

Here are the three common ways tennis data gets used incorrectly in player development.

1. Ratings/Rankings and Scores Are Outputs

Ratings matter. Rankings matter. Match scores matter, but they are outputs. They are not development metrics.

A match score tells you what happened. A rating tells you where a player currently sits in the competitive landscape. Neither tells you enough about how the player is building points, making decisions, creating advantage, or breaking down under pressure.

A player can lose 6–4, 6–4 and still show meaningful development. They may have improved their point construction, played better 1-3-5 patterns, or made better decisions at scores that matter that little bit more.

Equally, a player can win matches while reinforcing habits that eventually become performance ceilings. At 135TI, we've seen it too many times - a player who is tracking downwards or stagnating on their 135 Player Profile, for example, but still winning matches, particularly in the 12s.

They tell you the outcome. They don't assist with what we call "fact-based coaching".

2. Most Current Match Data Lacks Definition

Some match statistics sound useful:

• Points won on first serve.
• Points won at net.
• Winners and errors.
• Break points won.
• 0-4, 5-8 and 9+ rally length.

The issue is not that these numbers are wrong. The issue is that they either lack definition or they lack context, or both.

Take points won on first serve. What is that statistic trying to measure? The answer is 1st Serve effectiveness.

If a player serves an ace, they have served an effective first serve. But what if the first serve is in and a 16 shot rally ensues, concluding with the returner missing an easy volley in the net? Was the 1st serve effective in winning the server the point? Of course not. But it carries the same weight in a general data set like points won on 1st serve.

How about points won at net? How do we define that statistic? If you asked 10 commentators who use that statistic in their commentary, it's likely you would hear different definitions from all of them.

Without definition, good data and bad data get loaded into the same data set.

That's incredibly dangerous for development, because it can make a player or coach believe something is working when the number is actually hiding the real story.

Player development needs more than numbers. It needs context, definition and a framework that connects match information to the way a player actually plays.

3. Big Data Sends Mixed Messages

Big data has become fashionable in tennis. You have probably heard statements like:

These statements are often based on large samples of professional tennis points. And in that context, they may help describe broad trends in the professional game.

But describing professional tennis is not the same as developing a junior player, not to mention the problem of mixing unforced errors with forced errors to come up with the statement "70% of tennis is errors".

Professional players are still developing, but with different development priorities required compared to junior players.

ATP and WTA players have stable identities, physical maturity, repeatable pattern development and years of decision-making experience. Junior players are still building those things.

That means professional match trends should not automatically become junior development priorities.

The problem with “0–4 shots is 70% of tennis”

At face value, this sounds logical, and it's not actually wrong. We are supposed to infer from this statement that if most points are short, shouldn’t most training focus on short points?

Not necessarily.

Players do not just need to learn how to start points. They need to learn how to solve points, and solve them based on more than just "here's what I'm going to do." What about "who is my opponent?" "Whats the score?" "What are the conditions?"

Junior tennis is full of moments where players lose control of a rally, face uncomfortable court positions, need to adapt tactically, or must solve problems under pressure.

If development becomes too focused on short-point tennis, players can become good when points stay on script — but struggle when the rally changes shape.

That is why 135 does not simply group tennis into broad rally-length categories like 0–4. We break player profiling into more meaningful, individualized developmental segments:

• 1–3-5: the server’s first three shots
• 2–4-6: the returner’s first three shots
• 7+: extended rally

These phases ask different questions of a player.

The first phase shows how a player initiates the point. The middle phase shows whether they can adapt once the first pattern changes. The longer phase shows resilience, tolerance and decision-making under pressure.

The goal is not simply to know where points finish.

The problem with “70% of tennis is errors”

The same issue exists with broad statements about errors. If players are told that most points end in errors, the message often becomes simple: "Don't Miss".

Lumping all errors together creates passive players who are afraid to take the right risks, and passive players eventually hit ceilings.

The best players are not the players who simply avoid risk. They are the players who understand which risks are worth taking, when to take them, and how to recover when they do not work.

Development Players Are Not Miniature Professionals

This is the key point.

Big data can be interesting. Professional trends can seem compelling. Broad statistics seem like they help ask better questions.

The fact is they should not be used as a shortcut for junior development.

Junior players need a framework designed for growth, not simply a model copied from professional outcomes.

Better Understanding starts with the right Measurement

Rankings, ratings and scores are outputs only. Traditional match data uses information that either doesn't matter or is just plain wrong. Big data doesn't help players develop.

The statement "the numbers don't lie" is true, but it leaves out definition and methodology that often renders data invalid or unuseable.