The Summer of Jeff

The Qualifier Advantage

Posted in tennis by Jeff on July 13, 2010

By definition, qualifiers in a pro tennis tournament are among the lowest-ranked players in the draw. (Wild cards are sometimes lower seeded, and occasionally a player substantially improves his ranking before the cut-off date for tourney acceptance and the tourney itself. That’s why Thomaz Belluci was playing qualies at last year’s US Open despite a ranking well inside the top 100.)

So, it stands to reason that qualifiers would usually lose their first-round match; if they survive, their odds of getting further plummet with each passing round.

That doesn’t seem like what happens. Sure, a large number of qualifiers don’t make it past the first round, and sometimes the ones who make it past the first round did so because they drew another qualifier (or wild card) to open the tournament. But anecdotally, it seems that qualifiers do better than they’re “supposed to.”

That’s my first testable claim, one that I’m not going to test today:

Qualifiers perform better than their rankings suggest they would.

If that’s true, the more compelling question is, “Why?”  That’s tougher to test, but the reasons are worth some speculation.  Here are several possibilities:

  1. The hot hand.  In grand slams, qualifiers have to win three matches in a row.  In any tournament, they have to have won at least two.  Hell, in some USA Futures tourneys, qualifiers have to win four in a row.  Maybe the momentum is worth something.
  2. A short lay-off.  A player ranked in the middle of the top 100 is getting direct entry into most draws, but not winning very often.  He might go several weeks in a row in which he plays once, maybe twice per week.  So each week, he has a new match after a full week without any match play.  On the other hand, the qualifier has just played two or three matches.  The higher-ranked player has the advantage of being “fresh,” but how fresh is too fresh?  This factor would be difficult to separate from the hot hand, since a player who has recent match play is generally one who has been winning.
  3. A favored surface.  The main disadvantage of ATP rankings as a predictor of match outcomes is that they don’t distinguish between surfaces.  So if we use rankings, we make the false assumption that Andy Roddick is just as likely to beat Gael Monfils on clay as he is on grass.  So maybe the players who come through qualifying are ones who are best on the surface of that tournament.  Thus, their ranking doesn’t reflect their skill level on the surface, but their performance reveals it in qualifying.
  4. Rankings overstate the difference between players.  This is another avenue for research.  Clearly there’s less difference between #50 and #150 than, say, #1 and #10.  But how much less?  It’s amazing how much movement there is in the back half of the top 100–I would guess that over 150 players per year appear in the top 100.  So, if ranking points overstate the difference in talent level, it shouldn’t come as a surprise that a qualifier ranked #147 has a good shot at knocking off a player ranked #54.
  5. Unfamiliarity.  Maybe an up-and-coming player has an advantage against a more established opponent in their first meeting.  For instance, last week at Newport, qualifier Richard Bloomfield beat Christophe Rochus and Santiago Giraldo en route to the final.  Rochus and Giraldo aren’t exactly superstars, but Bloomfield would have a better opportunity to learn about their games than they would about his.  I doubt this theory is worth much.
  6. There’s nothing to lose.  Here’s a commentator favorite.  Bloomfield, once he got into the main draw, had “nothing to lose,” while all the pressure was more established players.  I’m not sure I buy that, and even if I do, I’m not sure it has much value here.  It would seem to apply to almost every match, so any calculation we make using player rankings would already have the “nothing to lose” factor built in.

Many of the same factors apply to wild cards, as well.  WCs would probably be tougher to test because so many of them have limited track records.  Some players get WCs for winning local junior tournaments, or upon returning for a long injury layoff.

In any event, there’s a lot to study here.

2 Responses

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  1. dq said, on July 16, 2010 at 7:06 pm

    You’re also missing the possibility that the qualifier is better right now than the ranked player. I believe the ranking are based on a year. If a player was ranked 50th 6 months ago and is now 80th, in the last 6 months he might only be the 140th best player. If the qualy was 150th 6 months ago and now is 120th, he might be the 80th best player over the last 6 months.

    • Jeff said, on July 17, 2010 at 5:19 pm

      It’s possible. Some work I posted earlier here suggests that ATP ranking points are actually quite predictive of match results. And in some cases, what you suggest is certainly true.

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