Platform Tennis Index

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.

While a player’s PTI reflects his/her ability, it is more precise to describe it as a measure of rated match performance. Players who routinely defeat the same opponents 6-0, 6-0 will have a stronger (lower) rating than those who defeat them 7-5, 7-5.

This could be because the 6-0, 6-0 winners were simply so much stronger than the 7-5, 7-5 winners. Or because the 7-5, 7-5 winners decided to keep the match “friendly.” This is consistent with the goal of using PTI to organize “good matches” vs. “not so good matches.”

There are several ways that a player’s initial PTI is determined/adjusted.

1. League Administrators and Tournament Directors work with the APTA to set default start ratings to apply based on the Division and/or Line of a player’s first match.
2. League Administrators and Tournament Directors can use feedback from teaching professionals and captains to manually set an Initial PTI for a player.

Regardless of how initial PTI ratings are set for players, the APTA and League commissioners will review player’s match results to determine if their performance was consistent with the initial start ratings and make modifications if the early matches show it was off.

More information: Initial Start Ratings - Defaults and Overrides

PTI ratings are a dynamic system and are updated frequently to incorporate new and corrected match results and player ratings.

Primarily, PTI ratings are adjusted after each match. The PTI algorithm uses the match type, match results (winner and game/set score), and the ratings difference between the 2 teams to calculate the adjustment.

For example: Alice (20 PTI) and Bob (28 PTI) play a match against Charlotte (24 PTI) and Doug (30 PTI). Alice & Bob have a team PTI of 48 vs Charlotte & Doug (54). Alice & Bob have a lower team rating and are favored to win the match.

If Alice & Bob win, this is the expected outcome, and will likely see a small decrease in rating to reflect the margin of victory. Charlotte & Doug will see a small increase of the same amount.

On the other hand, if Charlotte & Doug win, this is an upset and will be reflected by larger adjustments to reflect the unexpected outcome.

It would be reasonable to say that a PTI is changed through unexpected results (upsets) and fine tuned during expected results (when the favored team wins).

More Information: Expected and Actual: What do they mean? Why did my PTI change(when I didn't even play)?

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.

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.

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.

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 PTI ratings. Some of the more common uses for PTI include:

1. Tournaments: PTI is 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 is also being used to determine seeding and draw placements for tournaments.
2. Teams: Captains and/or Pros use PTI to help determine the appropriate teams for players within a club.
3. Leagues: Leagues can use PTI to help determine what division to place a new team in the league.
4. Line-ups: PTI is used to prevent lineup “stacking”.

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 PTI gets a little worse. The move is almost always only a few tenths of a point.

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.

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."

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. Leagues and tournament directors may make exceptions to this rule if they feel its appropriate (example: a team is ahead 6-0, 5-0, 40-love…and someone from the team ahead gets injured; a league or TD may determine not to award the win (for PTI purposes) to the uninjured team that was on the cusp of losing).

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.

Yes.

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

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).

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.

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.

That depends. You can make the argument either way. If I’m a favorite in five straight matches and win them all, my PTI will improve (albeit at a slow pace). Eventually my PTI will get to a level where it's tough for me to meet expectations. If I’m an underdog in five straight matches and lose them all, my PTI will gradually get worse to the point where it should be easy for me to outperform expectations.

For players who have played enough matches to have a fairly accurate PTI (at least 7, but ideally more than 20), your PTI is likely to live in a band of 5-6 points. If you’re “true north” PTI is a 25, it’s very possible you could get as low as a 22 and as high as a 28 during the course of a season depending on partners you play with, opponents you face, tournaments you enter, etc. Please don’t get hung up on a couple points move here or there. It’s a doubles game so there will be times when you are probably underrated by your PTI; conversely, there will be times when you’re probably overrated vs your PTI. The algorithm is a self-correcting mechanism which will make it difficult to keep you from your “true north” PTI for too long.

The amount of data factored into your PTI depends mainly on how long your league has been on Paddlescores OR whether and how much match data your league was able to import when moving over to Paddlescores. Some leagues have been on Paddlescores for many years; some were able to bring 4-5 years of match history with them when they moved to Paddlescores; others are starting with no data.

The core PTI algorithm is a follows:

• Team PTI is calculated as the sum of the players' PTI. 
• An “Expected” result between 0 - 100% based on the difference between the Team PTI. 

• An “Actual” result between 0 - 100% is calculated based on the match results.

• The Team PTI adjustment is calculated based on the difference between the Expected and Actual results.

• The Team PTI is split evenly between the 2 players. 

This core algorithm is an implementation of the ELO Rating System used widely in competitive sports and activities.

The PTI system adds additional adjustment multipliers based on:

• Increased Multiplier: 
  • 1.5x for main draw tournament matches 
  • 1x-2x for lowest confidence player in a match
• Decreased Multiplier:
  • 1x - 0x for PTI spreads between 17 - 21 unless underdog wins
  • 1x - 0.125x for higher confidence players in matches with lower confidence players
  • .5x for casual and ladder matches
• Skipped Matches :
  • Matches won by teams favored by 21 or more PTI points
  • Matches defaulted or won without date or score.

More Information : Expected and Actual : What do they mean?