ATP quality points: Djokovic still comes out on top

• Novak Djokovic, No. 1 in the ATP rankings, also would be No. 1 in a quality wins ranking
• Based on this, Juan Martin del Potro looks to be the biggest threat to the top four
• It also shows that Jo-Wilfried Tsonga is beating the top guys

Just like the WTA, there was a time when the ATP rankings took into account the strength of the opposition, but again like the women, the men abandoned their system of "bonus points" a dozen years ago.

But in a year when it's been difficult to choose among the "Big 4" of Novak Djokovic, Rafael Nadal, Roger Federer and Andy Murray, one way of doing it is by bonus points — looking at the strength of the opposition they beat along the way. This table below shows the average number of bonus points players earned in each tournament they played, using the same system as for the WTA players.

The results show that Djokovic remains the clear leader, and Murray is the clear No. 4. Nos. 2 and 3 are more interesting. Nadal and Federer are fairly close together — and, remember, this is based only on tournaments played. Nadal played his favorite part of the year, the clay season; he missed his worst, the indoor season. So it's pretty close.

By any measure, the Big Four are way ahead of everyone else. But look below
— based on these numbers, it appears that Juan Martin del Potro, not David Ferrer or Tomas Berdych, is the biggest threat to join the Big 4. And Jo-Wilfried Tsonga, who has declared that he wants to be part of the top five, is way down at No. 12 — he isn't beating his competition often enough to back up his ambitions.

Gael Monfils stands at No. 8, and certainly looks as if he could make a big comeback. Close behind is Tommy Haas, who clearly deserved his Comeback Player of the Year honors — he's top 10 in terms of the players he's beaten this season. Lleyton Hewitt and Sam Querrey, also returning from injury, are making real progress as well.

American Michael Russell's ranking has stayed around No. 100 for years — it doesn't seem likely that he will go much higher, but mark him down as a guy who takes down a lot of quality players. And though Lukas Rosol hasn't made much rankings progress since his Wimbledon upset of Nadal, that big result helps put him at No. 38 in quality points.

Oh, and about Alex Corretja's decision to play Nicolas Almagro and not Feliciano Lopez in the Davis Cup final: both Spaniards suffer under this ranking, but Almagro appears to be stronger in tense matches than Lopez.

To be included in the calculation, players were expected to have played at least eight ATP main draws.