33. The Clutch Index 2014 – better players win close matches

“Clutch play” in tennis means playing better when the match is close and the pressure is on. We sometimes make the error of mistaking close with lucky. But in terms of match outcomes, “luck” is a misnomer: over the course of at least this season and last season, it is better players who win close matches and it’s because when the match is close, better players are more able to play their best tennis.

So, the Clutch Index is an index I have created that is a proxy for mental strength on the ATP tour. At the top of the game (i.e the top 50), where players may arguably have similar skills and talents, it is those that are strong mentally that win tight matches and achieve higher rankings.

The Clutch Index is for ATP players only; I’m currently working on the equivalent version for the WTA tour. The 2013 edition is here.

Measuring clutch for The Clutch Index

My measure of “clutch” is simple. When a set reaches 5 games all, why do some players win more than half of those sets and some players less than half? At 5-5 the set is even. If luck was the determining factor, players would win or lose a similar share of these sets. That, as we will see, is not the case.

I score the players as follows (full methodology at the bottom): you get +1 point if you win a set 7-5 or 7-6; you get -1 point if you lose a set 7-5 or 7-6. I double the points for winning and for losing if the final set of a match goes to 7-5 or beyond (i.e. 7-6, or 8-6 9-7 etc in a grand slam match). Win the final set 7-6 and you score +2 points; your opponent -2 points.

For each player, I aggregate the total number of points for the season and divide that by the number of their matches that have featured a “clutch” set (7-5 etc).


What comes out is a strong correlation among the top 50 between a player’s ranking and their position on the Clutch Index. [The coefficient is -0.4 for those interested.]

It is fitting that in a year when the Big 4 hold on men’s tennis has been weakened and with players have talked about their growing self-belief in challenging the Big 4, that those who have embodied that successful challenge the most – Wawrinka and Cilic – lead the index that measures mental strength.  

Indeed, the correlation between ATP top 50 ranking and position on the Clutch Index is marginally weaker this year compared to last (see here) precisely because of the challenge to the Big 4.

The chart below plots the top 50 ATP ranked players (before this week’s tournaments in Tokyo and Beijing; x axis) against their Clutch Index score for 2014 (y axis). Accordingly, by ATP ranking, Djokovic is the blue marker furthest left, Nadal next to him, then Federer and so on. The marker furthest right is Jarrko Nieminen, ranked 50th

Clutch Index 2014 vs ATP Ranking (pre-ATP Tokyo / Beijing)



The correlation between ranking and position on the Clutch Index emphasises the importance of mental strength on the ATP tour. Beyond this there are several layers of observation and analysis. Here are a few:

Marin Cilic (2014 – Clutch Index ranking 1st; 2013 – 9th)

Cilic, the US Open champion, leads The Clutch Index so far in 2014. For a start, he has an impressive tie-break record of 20-8 and an overall clutch set record (i.e. including 7-5s or 5-7s) of 28-10. He has won 3 out of 3 matches that went to 5-5 in a deciding third set. Cilic has acknowledged the evolution of his mental approach with coach Goran Ivanisevic, who has brought the “belief to be more aggressive”.

A more general observation is that a match with a clutch set occurs 51% of the time for the Top 50. For Cilic, it is just 1 match in 3 – testament to him blowing away his opponents often before it got to the tail end of a set.

Stan Wawrinka (2014 – 2nd; 2013 – 25th)

Wawrinka’s clutch performance in 2014 is founded upon his 9-7 final set win against Djokovic in the Australian Open semi-final as well as 2 tie-break wins in his semi-final against Berdych. His overall record in clutch sets this year of 24-9 is evidence of the confidence and belief stemming from his grand slam breakthrough, as much embodied through his second set tie-break win in the Monte Carlo Masters 1000 final against Federer.

Tomas Berdych (2014 – 43rd; 2013 – 37th)

Speaking of Tomas Berdych, both in 2013 and 2014, Berdych has the poorest Clutch Index record of Top 10 players, losing as many clutch sets as he wins. Many have questioned why Berdych has not broken through and won a grand slam. The short answer on this data is that enough sets in grand slams gets tight and Berdych has not yet found a way to play his best tennis under pressure. When he wins he wins big: only 13 of his 39 wins this year have involved a clutch set; however 7 out of his 15 losses have had clutch sets.

Fabio Fognini (2014 – 3rd; 2013 – 16th)

Data often asks as many questions as its answers. In an index that claims to be a proxy for mental strength, how is the Italian number one, defined by his talent but also his in-and-out mental engagement in matches, ranked so highly on the Clutch Index? The answer is in the differential of when Fabio’s clutch matches occur. For whereas 19 out of his 35 match wins involve a clutch set (54%), only 4 of his 17 losses do (less than 25%). In other words, when the match score is tight Fabio generally finds a way to win. The issue for him is to get it consistently close in the first place.

Plenty more analysis to come. Please feel free to share any thoughts you have. Tables below for the Top 50 players sorted by Rank and by Clutch Index position. Methodology at the bottom. Thanks for reading.

Top 50 ATP players sorted by Clutch Index ranking


Clutch Index scores sorted by ATP ranking (Top 50 only)

33-Clutch-Index-ranked by ATP tank


Complete methodology for The Clutch Index


I have taken all ATP Tour main draw matches and men’s Grand Slam matches in 2014, a total as at 29 September 2014 of 2,188 matches. All the matches have to have been completed without retirement or walkover.

Points have been awarded to players as follows:

+1pt       – win a set 7-6 or 7-5

-1pt        – lose a set 7-6 or 7-5

+2pts     – win the final set of a match (3 set or 5 set) 7-6, 7-5 or 8-6, 9-7 etc

-2pts      – lose the final set of a match (3 set or 5 set) 7-6, 7-5 or 8-6, 9-7 etc

Example: in R16 (round 4) of the US Open 2013, Gasquet beat Raonic 6-7 7-6 2-6 7-6 7-5. In this match, Gasquet scores 3 points (-1 for losing the first set TB, +1 for each of the second and fourth set TBs, and +2 for winning the final set 7-5). Raonic scores -3 points (+1 for the first set, -1 for each of sets 2 and 4, and -2 for losing the last set 7-5).


* Clutch matches – a match involving at least one set with a scoreline of 7-6 (or 6-7) 7-5 (or 5-7), 8-6, 9-7 etc.

** Clutch score – the total of a player’s score totalling up his “negative” sets (eg sets lost 7-6 7-5) and his “positive” sets (sets won 7-6 or 7-5)

*** Clutch ratio – the key measurement. This is the Clutch score divided by the number of Clutch matches. It is important not to over- or underweight Clutch scores based solely on the number of Clutch matches.


Featured image: Associated Press / Charles Krupa


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