Platform Tennis Index

What is the Platform Tennis Index (PTI)?

PTI stands for Platform Tennis Index. It’s a rating system developed by the APTA, in partnership with the Paddlescores league management website, to rate the skill level of a player based on results from match data.

What does my PTI mean?

A player’s PTI is a number generally ranging from 0 to 80. Similar to a golf handicap, better players have a lower PTI.

An 80 represents a brand new player who likely has limited experience playing other racquet sports.
A 0 represents a highly skilled player who can compete at the very top national level.
The PTI rating system is a unisex rating system; men and women are rated on the same scale because there are many leagues and tournaments across the country that include both men and women.
The average PTI for league players is in the 50-60 range; slightly lower for men, slightly higher for women.
While it’s possible to have a negative rating, only 0.5% of the roughly 20,000 players rated currently have a negative rating.

How do players get an initial PTI?

There are several options to set a player’s initial Rating:

Use a default PTI based on a player's division/line number for his/her first match
Use match data from prior seasons to determine appropriate start rating
Have a pro or team captain assign an initial PTI (done through league commissioner)
Play in an APTA Live Scoring or Paddlescores hosted tournament (PTI will be assigned by Tournament Director)

How do PTIs adjust?

PTIs are dynamic, and adjust after match results are posted. The PTI algorithm uses the match outcome (win/loss, and % of games won) and the relative strength of the teams to determine the adjustment. Winning/losing the match is the most important factor in determining a PTI change.

For example: For example: Player A (a 20 PTI) and Player B (28 PTI) have a match versus Player C (24 PTI) and Player D (30 PTI). Team A/B has a combined PTI of 48 vs. Team C/D’s of 54. Team A/B has a lower PTI and is favored to win the match.

If Team A/B wins, this is the expected outcome. PTIs for A and B will decline a small amount; PTIs for C and D will increase by the opposite amount.

On the other hand, if Team C/D wins, this is an upset! PTIs for C and D will decline by a more significant amount while PTIs for A and B increase.

Large changes in PTI are achieved through upsets or lopsided victories between closely-matched teams. A heavily-favored team cannot improve its PTI by feasting on weak opponents.

What’s a Confidence Factor?

Starting with the 2019-2020 season, the APTA is incorporating a Confidence Factor into the Paddle Tennis Index algorithm. This innovation provides another dimension to further improve the adjustment of a player’s Paddle Tennis Index.

Confidence Factor ranges from 0% to 100%, and increases with each match played. A player reaches full confidence (100%) at eight matches played.

For a posted match result, players with lower Confidence Factors will have less of an impact on the Paddle Tennis Index of players with higher Confidence Factors. At the same time, the ratings of lower Confidence Factor players will adjust faster than others. This allows players to reach an appropriate Paddle Tennis Index more quickly.

Can I have my PTI changed?

There is no way to change your “current” PTI. Only your initial start rating or the confidence factor on your current PTI can be changed. Once/if one of those are changed, the algo will go back (overnight) and recalculate every match you’ve ever played to produce your new PTI.

To have either your initial start rating or your confidence factor changed, you need to petition your league’s PTI Committee. This is typically done through your team’s captain with an explanation for why an adjustment makes sense.

While the rating system is still new to some leagues, we are allowing League Commissioners to change initial start ratings for players in their respective leagues. Eventually, we’ll only allow initial start ratings to be altered by the APTA PTI Committee. A player or league commissioner will be able to petition the Committee in writing to propose a more accurate initial Index.

The Confidence Factor may be altered at the league level by a League Commissioner or League PTI Committee. Reasons to alter a player’s Confidence Factor include significant injuries; long absences (multiple months or years) from the game; a strong tennis player who is “figuring out” paddle and rapidly improving skill.

What exactly is PTI measuring? Is it like a golf handicap?

A golf handicap measures a golfer's “potential” because it throws out your worst scores and takes an average of your best scores. Your PTI doesn’t measure your potential because it captures all your matches. It’s a measure of your actual performance and not your potential.

Who is in charge of the PTI algorithm?

The APTA has formed a PTI Committee currently made up of 9 people from 7 different leagues across the country. This committee monitors how the algo is working and reviews suggestions for tweaking the algo during the off-season.

What’s the exact math behind the algorithm?

At this point in time, the APTA has decided not to publish the exact math behind the algorithm. We will revisit this decision each off-season. There is typically at least one person (PTI czar or committee) in every league that is familiar with the exact math behind the algorithm.

How do Leagues use the PTI system?

There are no standards currently in place for how a league could or should use the PTI system. Each league decides for itself whether and how to use PTIs. Some of the more common uses for PTIs include:

Tournaments: PTIs are used to offer tournaments at different skill levels. A tournament director can set any eligibility threshold he or she wants for a tournament (an individual threshold, a combined/team threshold, etc). PTI are also being used to determine seeding and draw placements for tournaments.
Teams: Captains and/or Pros use PTIs to help determine the appropriate teams for players within a club.
Leagues: Leagues can use PTIs to help determine what division to place a new team in the league.
Line-ups: PTIs are used to prevent lineup “stacking”.

Other common questions about individual PTIs:

I won my match but my PTI got worse; how is that possible?

While it’s a rare occurrence, it is possible to have your PTI get worse even if you win a match. The scenario where this happens is when a heavily favored team barely beats its opponent. While the favored team gets the winning bonus from the algorithm, the percentage of games won can miss expectations by enough that the winning team’s PTIs get a little worse. The move is almost always only a few tenths of a point.

I was a heavy underdog and almost pulled out a huge upset; why didn’t my PTI improve (or improve by more)?

This is the corollary to the previous question. The algorithm rewards winning first and percentage of games won second. Had the underdog team pulled off the upset and gotten the win, the PTI adjustment would have been large… well over a point, possibly close to two points.

Why did my match not count towards PTI; why was it “skipped”?

There are a couple instances where the algorithm will skip a match. The most common is when two teams playing each other have a combined PTI spread of 21 points or higher. That match won’t count towards PTI UNLESS the underdog team actually wins. When the combined ratings spread between two teams is between 16-21 points, the algo starts to decrease the weighting of the match (unless again the underdog teams wins). This is to prevent heavy favorites from being forced to blow out weaker opponents.

The other scenario where a match won’t count towards your PTI is if its marked as “Default”.

What happens if someone gets injured during a match and can’t finish playing?

If one full set has been played, the match will count towards your PTI. If less than a full set has been played, the match should be marked as “default” so it will be skipped.

Will PTIs discourage players from wanting to partner with weaker partners?

It shouldn’t. A weaker partner comes with a higher (worse) PTI which means the expectations for the outcome will be reflected in that higher PTI. It doesn’t matter whether your partner is better or worse than you… what matters is whether they can play to their PTI. You’re better off playing with a player rated a 50 who plays like a 45 vs a player rated a 5 who plays like a 10.

If a man and a woman have the same PTI does that mean they are the same skill level?

Yes

Why do PTIs move more than normal during tournaments?

Main draw tournament matches count 1.5x a league or ladder match. Backdraw tournament matches count the same as a league or ladder match.

What matches count toward my PTI?

Any league, ladder or tournament match entered on a Paddlescores site will count. Casual matches entered on a Paddlescores will also count but only 50% of a league match. Any APTA tournament that uses Live Scoring where the tournament director has entered scores properly will be imported into the PTI database (and count toward your PTI).

Why did my PTI change a different amount than my partner’s or my opponents?

If any players in a match are new to the PTI system, their PTI will have a confidence factor (CF) less than 100%. Players with CFs less than 100% will adjust more quickly than players with CFs of 100%. The lower the CF, the greater the adjustment. Your PTI will adjust the exact same as your partner’s if/when you have the same CF. Everyone’s CF reaches 100% once you’ve played seven matches that have counted toward your PTI.

What are cases where it’s hard for someone to improve their PTI?

It’s difficult to materially improve your PTI if you’re always a very heavy favorite. You aren’t rewarded much for beating teams you’re expected to beat handily.