Rob Minto

Sport, data, ideas

Tag: Rafael Nadal

Nadal, Berdych and the upper limit of winning streaks

462326540Tomas Berdych must be a relieved man. Having lost 17 times in a row to Rafael Nadal, he has finally snapped the streak at the Australian Open.

Had he lost, it would have been a new record. Tennis rivalries do often produce one-sided periods, but 17 wins for one player in a row is the upper limit. It’s the number of consecutive wins that Bjorn Borg had over Vitas Gerulaitis; that Ivan Lendl had over Tim Mayotte; and Lendl had over, surprisingly, Jimmy Connors.

Weirdly, the upper teens seems to be the limit in other sports streaks too: the Australian cricket team went on a 16-test winning streak in 1999 to 2001. Both New Zealand (twice) and South Africa hold the record of 17 straight test wins in rugby. And Spain’s football team had a 15-game winning run.

Is there a mathematical reason for 15 to 18 being the upper limit of streaks? If it were a coin toss, then probably yes. But sport isn’t a coin toss. The win streaks get harder as teams put pressure on themselves to perform, and opponents look to topple the team of the moment. Of course, it’s easy to give a bad performance, and teams get injuries, or retirements.

The tennis streaks mentioned above have ended at 17 as one of the players retired. The interesting thing about Berdych’s victory is that it is the first reversal. Nadal may have been under par, but the pressure would have been on Berdych to win, rather than in team sports where the pressure piles onto the streak holder.

So which is the next longest active head-to-head winning (or losing) streak? I can’t find a definitive list, but I wouldn’t be surprised if it’s Richard Gasquet against, you guessed it, Nadal. The scoreline is 0-13 in Nadal’s favour.

That quote

As Gerulaitis said after he beat Connors in 1980: “nobody beats Vitas Gerulaitis 17 times”. Except the ATP record shows that his losing streak against Connors was 12, and was 16 against Borg. (There is a walkover for Gerulaitis in 1978, which you might think counts as a win, but the ATP seems to not count them in the head to heads.) I have no idea where the missing 17th match is.

Nadal’s seeding: Wimbledon’s own subprime crisis

No one can be happy about this.

Grass court tennis has been something of an anomaly on the tour for many years now – there are only a handful of tournaments, and then the biggest catch of them all: Wimbledon.

So when the All England Championships garnered agreement back in 2001 that it could continue to re-jig its seeding, but only by accepting that it had to take the top 32 players in the world, it seemed like a victory for common sense.

And yet we are back at square one. Rafael Nadal is a two-time champion, three-time finalist. He’s just won the French Open. But because of his long injury, his ranking is #5 in the world.

No matter – Wimbledon can bump him up, to 4th or even 3rd seed, surely?

Except it hasn’t worked out that way. Wimbledon now use a formula to work out grass court credentials. It is basically a player’s ranking, plus 100% of grass court points in the last year, plus 75% of the year before.

And that is not enough for Nadal, who lost in R2 in 2012, but was a finalist in 2011. He is 5th seed, behind David Ferrer, who has been to the quarter final just once at Wimbledon.

This isn’t madness – it’s rational. But it fails the smell test. Ferrer isn’t going to win Wimbledon – whereas Nadal has a damn good chance. A decent formula has come up with a nonsense answer. And when the draw comes out on Friday, Nadal may well play any of Federer, Djokovic or Murray in the quarter-finals – a big shame.

This reminds me of the 2007-08 (and onwards) financial crisis. Essentially, the players rankings are a mark-to-market valuation of their rolling 12-month form. But we all know that they are a guide, and a fallible one at that. Otherwise the #1 ranked player would win every time.

What Wimbledon has done is add to that mark-to-market pricing their own extra value-at-grass quant formula, to try and iron out the errors in the value of players measured on other surfaces – concrete and clay, essentially.

But just like the subprime crisis which had its origins in the slicing and dicing of bad mortgages to come up with collateralised debt products, giving them an ‘A’ rating, Wimbledon has sliced and diced the grass numbers, and come up with an equally meaningless result.

Part of the problem is that Nadal and many other players don’t play the grass court warmup events – and therefore don’t have grass ranking points from lesser tournaments – as the French Open and Wimbledon are too close together in the diary. The players need rest instead.

This could all be solved by spreading out the French and Wimbledon tournaments, and creating a grass masters series event in between, to give the grass season proper ranking weight – but everyone has known that for years, and it’s not happened yet.

But unlike the financial crisis, the result of using poor incentives and ill-judged computer formulae won’t result in economic armageddon. It will just skew the tournament a bit and mess up the finals schedule, annoying a few advertisers and a lot of fans. Still a pity though. The sport deserves better.

Why Nadal-Djokovic may be the best tennis rivalry ever

French Open final, 2012

Tennis thrives on great rivalries – they are almost more famous than the players themselves. Borg-McEnroe, Sampras-Agassi, Federer-Nadal.

But the current rivalry between Novak Djokovic and Rafael Nadal may be the best ever. Here’s the killer fact why:

They are the only pair (in the men’s game) to have contested each of the four major finals. No-one else has done that – not any of the rivalries I mentioned at the start, nor even any of the pre-open era rivalries such as Laver-Emerson.

Why is that important? Well, it shows that they are both hugely talented on all surfaces, and have stamina to get to many major finals. And although this Friday’s meeting at the French Open is a semi rather than a final, due to Nadal’s ranking slipping after a long injury, who would bet against them overtaking the record of eight slam finals held by Federer-Nadal?

Which makes you realise how many finals Nadal has played against Federer and Djokovic – only three of his 16 major finals have been against other players (Soderling, Berdych and Puerta, winning them all).

The BBC (wrongly) stated that: “The Monte Carlo final [earlier this year] was the pair’s 34th meeting, making their rivalry the most prolific in the modern game, with Nadal leading 19-15 overall and 12-3 on clay.”

Update: the BBC updated the story, thanks to Piers Newbery.

Not quite. Lendl and McEnroe played 36 times. But that’s just another milestone soon to be passed by Nadal-Djokovic. Only injury can prevent them breaking several more records.

Djokovic vs Federer vs chance: is the draw fixed?

On Friday, Roger Federer and Novak Djokovic line up in the semi-final at Wimbledon. Although they have never played each other on grass before, a semi-final meeting has a very familiar ring to it.

Well, that’s because it is familiar – and a bit too frequent, when you look at the odds.

In fact, since Djokovic broke into the top 4, it is amazing how many times he and Federer have been placed in the same half of the draw. For those unfamiliar with how it should work, here it is:

  • The number 1 and 2 seeds are placed at opposite ends of the draw. Then, the 3rd and 4th seeds are picked at random and placed in one half or the other, away from the top 2 seeds so that they can only meet at the semi-final stage.
  • For many years, Federer was #1 in the world, with Nadal #2 and Djokovic #3 or #4. Now, Djokovic is #1, with Federer #3. Never in a slam have Federer and Djokovic been 1 and 2 seeds.

So, to recap: for since half way through 2007, for each of the four slams in a year, it has been a 50:50 chance that Federer and Djokovic should end up in the same half of the draw.

In fact, since Djokovic has broken into the top 4, (which has coincided with an ever-present Federer in the top 3), they have been in the same half of a grand slam draw 16 times out of 21.

To get 16 heads flipping a coin 21 times is not good odds. For what should be a 50 per cent chance, it is running at over 76 per cent. That looks suspicious.

And in 2009 and 2011, they were in the same half for EVERY slam. That’s a 1 in 16 chance for the year, repeated.

Overall, unless my statistics is letting me down, the chance of 16 out of 21 coin tosses coming up heads is 0.0097 – that’s the binomial probability. Here’s the calculator I used – enter 0.5, 21 and 16 to see the results. That’s not very likely.

[Aside: They are such good players, that out of the 16 times they have been in the top 4 seedings and drawn in the same half, they have managed to get to play each other 9 times, with one or both players going out before the semi stage 7 times.]

Why would you want to play Federer and Djokovic in the same half? To get Nadal in the final, that would be one possibility, to try and engineer more Nadal-Federer finals. Or, more likely, it’s just chance. But a few more Federer-Djokovic semis, and perhaps the players should be hiring statisticians as well as dieticians.

Here’s the data in a Google spreadsheet.

Picture of the week: Nadal in thought

Prior to his French Open defence, here’s Rafael Nadal looking particularly contemplative.

The limits of sports stats: the example of Nadal and the WSJ

This year in tennis is been all Djokovic and that winning streak. The narrative of sports is always about who is “the Man”, so therefore, Rafael Nadal must be a spent force.

The Wall St Journal have, they think, proved it. In their piece Nadal Looks Surprisingly Human in Paris they look at the stats of Nadal’s first four matches this year, and compare to the years he has won before.

Nadal’s stats don’t reflect a full-blown disaster. But compared to his first four victories in the years he won here, Nadal is spending on average a half hour longer on court and breaking opponents’ serves far less often. All this despite not playing a single seeded opponent so far.

What’s wrong with this? First off, players who are seeded CAN’T meet another seed until the third round anyway, so that’s hardly stunning. Let’s look a bit more at the stats they cite.

2011 85.5% 39.7% 62.8% 85.7% 2:52
2010 85.2% 50.9% 68.2% 100% 2:18
2008 87.8% 65.2% 76.8% 100% 2:05
2007 86.8% 50.9% 68.9% 100% 2:14
2006 81.8% 43.9% 62.9% 85.7% 3:04
2005 87.7% 44.6% 66.4% 92.3% 2:09

Sources: ATP World Tour, Stats Inc.

His average match length is high, but it was higher in 2006 when he won the title – hardly shocking. The only 2011 stat quoted which is worst in the list is the percentage of return games won – 4 per cent lower than the next lowest. Four per cent, which works out at about 2.5 games on the opponent’s serve that he hasn’t won in 4 rounds – less than a break of serve less per match.

So we have boiled Nadal’s struggle down to about a break less per match from 2006, perhaps two per match from his peak, plus a bit more time on court.

It’s hardly evidence of decline. But stats are like that. They don’t always show what seems evident to watchers and commentators. They don’t show the workrate, the struggle on points, the extra deuces, the attitude. Perhaps those things are there, perhaps we’re seeing what we want to see to fit the narrative. Let’s see what happens from here to the final.

Tennis: A rivalry in decline

Lost in all the battle of the streaks – Nadal on clay vs Djokovic in 2011 – was the fact that Nadal and Federer met again in a semi final on Saturday.

It’s a bit of a comedown for the greatest rivalry * in modern tennis. Nadal and Federer have played two semis in a row now, after previously playing in eight finals straight. Overall, of their 24 meetings, 18 have been in finals.

This is going to happen more now that Djokovic is number 2, and closing in on the top spot. At every big event there is a good chance they will be in the same half of the draw.

While nothing lasts forever in sport, I do still hope they play another big final this year. Strangely, it’s been over two years now that they met in a slam. The last meeting was the Aussie Open of 2009, which was a great match.

* greatest rivalry = based on the seven slam finals contested, two more than the next rivalries of Sampras-Aggasi and Lendl-Wilander; and on the time at number 1 and 2 together in the rankings (most of the last six years).

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