Rafael Nadal‘s two-year ranking system would favor a few veterans at the expense of everyone else. My algorithm is too complex for players and fans to use on a weekly basis. But there is always an undercurrent of dissatisfaction over the current system.

The rankings serve two main purposes, each of which we must keep in mind as we think through a better system:

**Entertainment.**The fans want to know who’s number one. No system will ever be perfect, but if the ranking system told us that Nadal outranked Djokovic despite losing to him several times in a row, the system would lose credibility.**Tournament entry.**Rankings determine who gets direct entry into tournaments. A biased ranking system would keep stronger players out of tournaments while letting in lesser players.

A system that is good for one of these purposes is generally good for the other. In an ideal world, the rankings would show us who is playing the best *right now*, carefully defining “right now” to avoid an unnecessary focus on current hot streaks. Another way to look at is that the rankings should be as predictive as possible. If underdogs are constantly winning, that doesn’t mean tennis is a sport full of triumphant underdogs, it means we’re ranking players incorrectly!

The current system isn’t that bad. There are three main problems, however:

**Last week is equal to last year.**The winner in Miami this week will gain 1000 points. Those 1000 points will be counted in his ranking next week, in six months, and in 51 weeks. In 53 weeks, though, he’ll have zero points. If we’re trying to measure how good he is, a tournament 51 weeks ago isn’t nearly as informative as his tournament last week. And if we insist on using his result from 51 weeks ago, why not his result from 53 weeks ago?**Surfaces are interchangeable.**Milos Raonic won a slew of matches on indoor courts last spring, which earned him a seed at the French Open. Now, I love Milos, but did he really deserve a seed at the French, despite virtually no professional experience on clay? Performance on one surface translates to other surfaces to some extent, but (obviously!) all surfaces are not created equal.**All opponents are equal.**In the Miami third round, Andy Roddick beat Roger Federer … then lost. He’ll get 90 points. Kei Nishikori beat Lukas Rosol … then lost. These sorts of differences sometimes even out over time, but must we trust that they will? Roddick’s achievement this week is much more impressive than Nishikori’s, and should be treated as such.

We can fix all of these problems with simple arithmetic, making tweaks to the system that any player or fan can understand.

In these solutions, the exact details don’t matter. The most important thing is simply to acknowledge that not all matches are equal.

**Last week is worth more than last year.**In my system, last week is worth a little bit more than the week before, which is worth a little bit more than the week before that, and so on. Here’s a simple way to incorporate that into the ATP system:*After four months, tournaments are worth only 80% of their original points. After eight months, tournaments are worth only 60% of their original points.*That way, the drop off is more gradual, and Indian Wells is worth more than, say, the 2011 Rome Masters. If Nadal still wants two years, this can easily be extended to cover two years of results–after a year, 45%; after 16 months, 30%, after 20 months, 15%. Now everybody’s happy!**Separate surfaces, separate rankings.**There will always–and should always–be a single most important ranking list, encompassing all surfaces. But for tournament entry, why not do better? For example, create a clay list by doubling the point value of all clay tournaments and leaving the others alone. David Ferrer and Carlos Berlocq will rise; John Isner and Kevin Anderson will fall. Any tennis fan knows this happens, so tournaments should determine entry this way, as well. After all, Wimbledon has long used this sort of approach for seeding, if not for direct entry.**Bonus points for beating top players.**The WTA used to do this, and it’s the least straightforward of my suggestions. It’s so important, though, that a little complexity is worth a lot. Let’s say 100 points for a win over anyone in the top 3; 75 points for beating anyone ranked 4, 5, or 6; 50 points for a win over anyone else in the top 10, 30 points for beating anyone ranked 11-15, and 10 points for a win over anyone ranked 16-20. Mega-upsets like those scored lately by Isner, Roddick, and Grigor Dimitrov tell us something important, and the rankings should listen.