French Open 2018: Nadal rightful favourite, but Thiem the value

Prior to the Australian Open, I wrote about the difficulty of assessing the chances of Novak Djokovic, who my ratings still considered to be the best player in the world, despite 18-months of indifferent form or absence. At the time, the numbers had him as a favourite in a head-to-head against Roger Federer, yet even ardent Djokovic supporters would have found it difficult at that time to suggest that the Serb was the better player of the two.

The Djokovic conundrum highlights a paradox of ratings systems like the Elo-based model that I use. The greatest strength of these ratings is that they avoid recency bias: the tendency for punters to overreact to the latest performances; preferring a longer-term view of form that is ultimately more predictive.

But in this strength of rating systems is also a weakness: when a recent decline in form is a result of a fundamental change in fortune – a significant injury, for example – the numbers fail to adjust quickly enough. The ratings become most inaccurate when injuries lead to lay-offs. A player can have a significant period of absence without any matches, meaning their rating remains at a pre-injury peak on their return, when it is unlikely they will play at anywhere near their best level for a number of matches.

Although we certainly now know more about the level of form that Djokovic has returned with, it is likely that his rating still overvalues his chances. Prior to the start of the clay-court tournament in Rome (which is in progress at the time of writing), Djokovic had played 12 matches since his return at the Australian Open in January, winning only half of them. This compares to a career-average match win-rate of 82%. In that same period, my rating for him has dropped by just over 100 (which suggests that he would have around 15% less chance of winning a match against an average opponent).

Using the quick-and-dirty calculation that I used prior to the Australian Open, I would predict that Djokovic’s rating has further to fall still, but herein we perhaps return to the strength of these types of rating systems: whilst Djokovic may struggle after a lay-off like any other player, he is probably better equipped than most to recover his best form more quickly, something he is trying to do by changing his coaching set-up and re-employing his old mentor, Marian Vajda.

Nonetheless, even with Federer’s absence for the third clay court season in a row, I would not entertain backing Djokovic for the French Open at his current odds of around 17.00, viewing him as more of a 50.00-shot.

Thiem the value against solid favourite

This perhaps makes Rafa Nadal’s odds of 1.48 look even more appealing. Despite his own struggles of recent years, the Spaniard is the deserved favourite to win his 12th title at Roland Garros. He returned from injury to win two Davis Cup matches at the start of April, before going on to win clay titles in Monte Carlo and Barcelona. At the time of writing he is about to play in the quarter-finals in Rome and looks to be progressing there with his usual imperiousness.

That’s not to say that Nadal is a certainty. Dominic Thiem, who beat Nadal in Madrid, has reached the semi-final in Paris for the last two years and, were the two to meet, if narrowing my ratings to only consider clay-court form, Nadal would only be a 1.55 favourite. Now, considering Thiem is available in the outright market at 14.00, he is likely the value bet.

Others to consider are Alexander Zverev (14.00) – profiled recently by Ralph Ellis – Kei Nishikori (65.00) and David Goffin (50.00) who, alongside Nadal, Thiem and Djokovic, complete a clay-court world top-six of players likely to play at the French Open. We’ll know more when we see the draw.

What’s perhaps most interesting going into the second grand slam tournament of the year, though, is the relatively depressed nature of the men’s game. Only four players in my top 20 are currently rated at 95% or more of their peak rating, with only the youngsters, Hyeon Chung and Borna Coric, seeming to be on-the-up. The top four are especially depressed, with the lowest average rating between them that I have ever recorded.

It seems like commentators have been predicting a changing-of-the-guard for several seasons. Now, the numbers are starting to support the sentiment. Whether the new clutch of up-and-comers will be able to take advantage and convert their promise into grand-slam tournament wins remains to be seen and, in Nadal at least, the old guard may just put up some opposition.

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