Jordan Spieth and Jason Day didn't play competitive golf this weekend. Nonetheless, they swapped places on Sunday in the Official World Golf Ranking.

Day is the new No. 1 in golf's ranking of record, taking the spot back that Spieth earned with his win at the Tour Championship, which clinched the FedEx Cup in September. Rory McIlroy, who finished T-26 at the Frys.com Open on Sunday, remains third.

So, how does this keep happening? Here's a brief -- as we can make it -- explanation of the Official World Golf Ranking formula.

The OWGR formula is computed over a rolling 104-week (or two-year) basis. Players earn points when they compete based on two factors: the strength of field, as determined primarily by the number of top 200 players in an event, and where they finish in a tournament. When players earn points, they maintain their full value for 13 weeks, or one-quarter of a year. In the 14th week after points are earned, they start to lose value in equal increments for the next 91 weeks, before they become worthless. A player's ranking is based on how many points they have banked currently over the number of tournaments they've played in the current 104-week period.

If you got through that, then this part should be easy. Since tournaments don't always fall on the same date and players don't always keep the same schedules from year to year, there are times when players lose more points than expected and suddenly change ranking. It just so happens, in this case, to wind up with the top two players in the world swapping places.

Spieth took No. 1 from McIlroy after his runner-up finish at the PGA Championship. After a two-week reign, Spieth ceded the top spot back to the Ulsterman after The Barclays, in which McIlroy didn't play. Spieth then got it back a week later. McIlroy got it back for the off week of the PGA Tour playoffs. Day took No. 1 after winning the BMW Championship. Then Spieth's East Lake win got him back to No. 1.

And this kind of thing will keep happening for a while. Day won't play again until the Hero World Challenge in December. Spieth will play that event and, before it, the WGC-HSBC Champions. McIlroy could pass them both by virtue of his finishes in the European Tour's four-event Race to Dubai Finals Series.

Ryan Ballengee is a Yahoo Sports contributor. Find him on Facebook and Twitter.

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