The Fatal Flaw of Nadal’s Two-Year Ranking System

Italian translation at settesei.it

Now that Rafael Nadal has resigned from the ATP player council–apparently because no one took his two-year ranking plan seriously–we’re likely to hear a bit more about this alternate approach.

Presumably, Nadal’s method would count the last 104 weeks (two years) of results instead of the last 52, as is currently the case.  As far as I know, he isn’t pushing for any other adjustments.  As long as that is the case, the rest of the council (and the ATP in general) is right to ignore Nadal’s plan: It would do significant damage to the sport, without much in the way of benefits.  It would drastically slow the rise of young players, but change little for guys at the top.

Ultimately, the question is over the purpose of the ranking system.  If it is to reward past performance, a two-year ranking system may be appropriate.  If it is to rank competitors by their current level of play, treating a tournament 22 months ago the same as last week’s tournament is flat-out wrong.

Consider what the present ranking system tells us.  By equally weighting tournaments over the last 52 weeks (with more points for more important events, of course), a player’s ranking is the average of how good he has been over the last 52 weeks–in other words, it’s a approximation of how good he was 26 weeks ago.  For most players, this is a decent estimate of how good they are right now.  If we go to a two-year system, the rankings would be an estimate of how good players were one full year ago.  Yikes.

The most obvious casualties of such a system are young players (or any players, really) on the way up.  Even with the current system, the rankings take some time to catch up with a rising star like Bernard Tomic or Milos Raonic.  When Raonic had his great run in early 2011, the rankings were still counting a bunch of challenger results from one year earlier.  In a two-year system, Raonic’s more recent results would count for even less.  It would take twice as long for such a player to establish himself.

The clear beneficiaries, of course, are the opposite type of competitor: established players who are declining or injured.  If a player is consistently good, it really doesn’t matter how the ranking system is calculated–just about any way you slice it, Djokovic, Nadal, Federer, and Murray would be the top four.  But the players who benefit are the ones who posted good results between 52 and 104 weeks ago, and haven’t done nearly as well since.  Right now, that means injured players like Robin Soderling, and declining players like Andy Roddick and Fernando Verdasco.

Should Roddick and Verdasco continue to be rewarded for their play in 2010?  To me, anyway, the answer is a clear “no.”  Even with Roddick’s sharp decline, he will probably still earn a seed for the French Open.  Does he deserve more than that?

But what about Soderling?  He hasn’t played since June, and his ranking has fallen to #30.  Unless he returns in the next three months, he’ll fall off the list altogether.  If there is a case for Nadal’s system, this is it.  But the ATP already has two methods in place to protect players like Soderling: protected rankings (PR) and wild cards.  Players injured for a certain length of time are able to use a PR (equal to their ranking when they last played) for entry to a set number of tournaments.  Until recently, Tommy Haas was still using a PR of 20.  Soderling would have a PR that would get him into enough tournaments to rebuild his ranking, assuming he comes back with any semblance of his previous form.

Of course, there’s also the wild card.  When Soderling returns, even if he is unranked, every 250- and 500-level tournament would hand him a wild card without a second thought.  This makes PRs even more valuable than the ATP intended them to be: Haas, for example, has been able to use his PR of 20 for so long because many tournaments gave him wild cards.  He could save the PR for when he needed it.

The only disadvantage to PRs and WCs is that these players aren’t seeded.  But really, after sitting out for a year, does a player deserve safe passage to the third round?  I find it hard to believe that they do.  And if this is really such an important issue, perhaps a player such as Soderling could be granted the lowest seed (e.g. 32, at Indian Wells, Miami, or a slam) two of the times he uses his protected ranking.

To recap: A simple two-year system would retard the rise of young players, forcing them to prove themselves for twice as long as is currently the case.  It wouldn’t affect consistently good players.  It would help players on the decline who probably don’t deserve help.  And top players returning from injury have little problem entering tournaments; Nadal’s approach would just get them seeds.

But Jeff, doesn’t your ranking system use two years of results?

Yes, I was getting to that.  It’s crucial to distinguish between using two years of results (acceptable) and weighting all results equally (unacceptable).

The biggest problem with the ATP ranking system as is–and it would be an even bigger problem with a two-year system like Nadal’s–is that it treats long-ago tournaments as equal to yesterday’s tournaments.  The winner of the 2012 Indian Wells event has 1000 points on his ranking.  The winner of the 2011 Miami even has 1000 points on his ranking.  The winner of the 2011 Indian Wells event has … zero points on his ranking.

How a player performed 18 months ago, or 20 months ago, has some predictive value.  But not nearly as much as the predictive value of their more recent performances.  In slight support of Nadal’s case, this is particularly true of players returning from injury.  My system never removed Juan Martin del Potro from the top 10 or so; using a one-year system, the ATP rankings saw him drop far out of the top 100.

If you are to use two years of results, it is absolutely imperative to differentiate between recent results and older results.  In fact, even a simple approach of this sort would improve the current 52-week system.  My algorithm weights results one year ago about half as heavily as last week’s, and two years ago roughly one-quarter as heavily.  The weighting is not simple, and thus would be inappropriate for the ATP system, which must be easily understood by both players and fans, but it points the way toward simpler solutions that might work.

That’s enough for today.  Check back tomorrow, when I’ll go into more depth about how the current ranking system can be improved.