How can Jon Rahm jump to No. 1 in the world with a win at Torrey Pines? We'll help with the math

A year ago, Jon Rahm was the 137th-ranked player in the world. With a successful title defense at this week’s Farmers Insurance Open, he will move to No. 1 in just 44 starts. Crazy, right?

To put that potential ascent in perspective, it took Tiger Woods 38 starts (21 of them as a professional) to reach the top of the Official World Golf Ranking for the first time in 1997. Of course, Woods is the true outliner.

Meanwhile, Jordan Spieth, whom Rahm replaced at No. 2 after last week’s win at the CareerBuilder Challenge, got to No. 1 for the first time in his 86th start.

“It’s hard to believe, to be honest, passing Jordan Spieth, three-time major champion. I only have two [PGA Tour] wins, he’s got 10-plus, right?” Rahm said on Sunday in Palm Springs. “I never thought I was going to be at this point in my life right now, especially the way I won both victories, it couldn’t be anymore different than the other.”

The same could be said when comparing Rahm to Dustin Johnson. The current No. 1 has more wins (eight to five worldwide), more top-five finishes (20 to 16), more top-10s (26 to 19), more top-25s (37 to 26) and fewer missed cuts (4 to 7) over the past two years, yet the 23-year-old Spaniard can supplant him atop the OWGR this week.

“I’m a little surprised,” said one highly-ranked player. “He’s had an unbelievable year-and-a-half run, but it’s hard for me to believe DJ, Jordan haven’t done more.”

So how exactly is it that Rahm can replace Johnson at No. 1? The short answer revolves around recent success. And math.

Let’s try to break it down:

The basic tenants that make up the formula for the OWGR include results over a two-year period, with the points available varying at each event (the better the field at the event, the more points players can earn) and the points a player accumulates depending on when the tournament took place (points earned decrease over time). Also key is a player’s divisor, or the number of events he has played.

In terms of recent success, any tournament played in the previous 13 weeks retains full point value. Beyond that, the points decline at a rate of 1.09 percent until they fall off (out of the two-year window).

For Rahm, that means a win at Torrey Pines would give him three victories and a runner-up in the last 13 weeks, meaning he’s getting max value for those performances. Conversely, Johnson, who isn’t playing at Farmers, would have a T-9, win and T-14 in his last 13 weeks. Comparing the two, Rahm currently retains 78 percent of the points value he originally earned while Johnson only retains roughly 51 percent.

Then there’s the aforementioned divisor, which is set at a minimum of 40 and a maximum of 52. Again, this is where Rahm benefits currently since he has played fewer events over the two years than Johnson. Rahm’s divisor is set at the minimum value allowed of 40 (he’s played just 39 events in the two years) while Johnson’s is 46. So, while Rahm has earned only 383.51 valued points (far fewer than Johnson’s 502.80), his smaller divisor helps keep his average high (9.5876, just shy of Johnson’s 10.9303 average).

But wait, Johnson won a major in that span. Shouldn’t that count for something? Well, yes, it doess, but it’s worth is decreasing as we are 18 months removed from the triumph at Oakmont. (Rahm, by the way, has just one top-25 in a major over the last two years, a tie for 23rd as an amateur at that Open at Oakmont won by Johnson.)

“DJ is totally deserving of it, or Jordan,” one player said of the No. 1 ranking. “They’ve won a lot and played well and won majors. I just think the divisor should be a minimum of maybe 30. [Rahm] totally deserves to be way up there, but without winning a major and only two times on [the PGA Tour] it’s like, ‘Really?’ ”

Yes, somehow, really.

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