Explaining the numbers: ATP Media’s Skill Set Index

ATP Media have introduced an innovative new ratings system for the Nitto ATP Finals – but what’s the logic behind the numbers?

The ‘Skill Set Index’ is a brand new concept in which a tennis player’s attributes are split into four categories – each of which contribute to an overall ‘Skill Set Index’. The categories are Under Pressure, Aggression, Defence and Endurance.

For each category the player earns a score out of 100, and their overall score is an average of the four categories. Each of the data points are weighted differently in their category depending on how important they are. The data has been generated from both the Hawk-Eye on court cameras and from the data logged by the chair umpire using his PDA device.

Under Pressure:
• 1st serves made on big points (30-30, 40-40 and break point down)
• Unforced errors on big points
• Matches won after losing the first set
• Win ratio vs top 10 ranked players
• % break points saved
• % break points won
• Average points won per tournament

• Average rally hit point
• % shots hit on the rise
• Average topspin groundstroke speed
• Rally shots hit within 50cm of the lines
• Aces per match

• Forced errors per match
• % shots hit on the run
• Average shot depth on the run
• % returns made
• % returns hit with slice

• Deciding set record
• Distance run per match (winning match)
• Average length of winning match
• % rallies won over nine shots
• Change in topspin speed (Set 1-Set 3)

Each category will be scored out of 100, and the average score of the four categories gives an overall score which is also out of 100.

The data has been accrued from the Masters 1000s tournaments, apart from the data point ‘average points won per tournament’ where the points accrued in Grand Slams, 500s and 250s have also been accounted for.