“She has a chance.”

That was the best the commentators at the 2012 Olympics could muster for the introduction of 15-year-old Katie Ledecky, who entered the finals of the 800-meter freestyle event as a virtual unknown. She had the third-fastest time in qualifying, but had no track record and no other medals in a year when the vaunted United States swim team ultimately won 31. Eight minutes, 15 seconds later, she was a gold medalist. Four years later, she is the most dominant swimmer on Earth.

That Ledecky will repeat in the 800 meters this year is certain, save for whatever allowances we must make for the potential for injury or planet-killing asteroids. Her mark of 8:06.68 is over 7 seconds faster than any other woman in history. She hasn’t been challenged at this distance for so long that it’s unclear how fast she can go. She’s almost as much of a favorite in the 400-meter freestyle, where she owns the world record and is the first woman to swim the event consistently in under 4 minutes. And despite being known as a distance swimmer, she is also the world champion in the 200-meter freestyle and the fourth-fastest woman in the event this decade.

But Ledecky’s expected gold medal tally doesn’t do her justice. Not even close.

Katie Ledecky is all alone

There are swimmers with more versatile repertoires — Michael Phelps’s 18 golds (and counting) is safe for now — but Ledecky specializes in the stroke designed to get you from point A to point B as fast as possible. Her races and her career essentially follow the same pattern — the more she swims, the more she separates from the field:

The black line is the average of the 50 best times at each distance since 2000. The top 200 times for each distance since 2000 are also plotted, with light orange lines each representing one swimmer.

As you can see, Ledecky is pretty much the Secretariat of swimming.

It’s a shame that the Olympic Games don’t include the women’s 1,500-meter event. Ledecky is so fast that her pace over 1,500 meters is faster than any other woman in history has managed over 800 meters. Wrap your head around that for a second: If Ledecky’s 1,500-meter record in 2015 were her only swim, she would have broken Rebecca Adlington’s 800-meter world record — that had stood since 2008 — in her first 800 meters.

With no real competition at distances of longer than 400 meters, we need new points of comparison. As I’ve written about before, her 800-meter record is marching its way through history as among the fastest swum by man or woman. She’s faster than the 1960 Olympic gold medal-winning men’s 800-meter relay (4×200) team, and she’s faster than any single person in history through 1975. She has cleared Tim Shaw and most of Stephen Holland’s records and could soon erase the Australian legend completely.

There’s dominant and there’s dominant and there’s dominant

Entering these Olympic games, at just 19 years old, Ledecky is already the most dominant freestyle swimmer in the modern era. To demonstrate, I looked at the top swims by the 50 top male and female swimmers at each distance. Using those as a baseline, I charted the top swims by the top 200 swimmers for each gender at each distance, relative to the top 50 (in standard deviations). In essence, this shows us how good each swimmer is relative to the best that each event has had to offer this century, and allows us to compare across events and genders:

Ledecky’s performance at 800 meters is the most any swimmer has dominated any distance, followed by her performance at 1,500 meters. The next three most-dominant swims were all set in the controversial summer of 2009 record frenzy that led to FINA’s banning of full-body and nontextile swimsuits. Then there’s Ledecky’s 400 meters.

And don’t sleep on her raw speed. Despite having unparalleled stamina, her 200-meter performance is nearly two standard deviations above the mean — of the top 50 of all time — in its own right. While she failed to qualify for the 100 meters at these Olympics, she is still well within the 50 fastest women (37th fastest since 2000) at that distance, and she’s still improving.

Rapidly.

Just the beginning

We know that the dropoff in speed that Ledecky shows over distances is uncannily flat. We don’t know how fast Ledecky can get.

We do know that her trends look good at every distance. USA swimming has times from all of Ledecky’s officially recognized races going back to her youth. But let’s pick up in 2010 — just two years before her London gold — when she was 13:

The gray dots each represent one of the 500 swimmers (of any age) at each distance who posted the fastest times and reflect those times versus the dates they were posted.

Ledecky has favorable-looking trends — both over all races and for her personal bests — at every distance. She has set personal bests in the 100, 200 and 800 this year already, after having personal bests in the 50, 100, 800 and 1,500 last year. Her best events are flattening out a bit (as we would expect), but even there it is difficult to gauge because she has been so far ahead of the pack that she hasn’t been pushed.

Even if Ledecky’s progression is normal, at 19 she should have years of improvement ahead. Generally, top female swimmers peak at older ages over shorter distances. The average age of a swimmer posting a personal best in the top 50 in a distance event (800m-1,500m) is 20. At middle distances (200-400m) it’s 22. At sprint distances (50-100m) it’s 25.

Ledecky’s consistent improvement at sprint distances, combined with her continuous, almost nonchalant dominance over longer distances, leaves me highly intrigued about the future possibilities.

Could she be the first woman to swim 800 meters in under 8 minutes? How about the first person to set world records at four different distances since Tim Shaw more than 40 years ago? Those are both fair bets for the future — and unlikely but still on the table for these games.

Beyond that, who knows? How about 1,500 meters in 15 minutes? Or becoming the first person to hold all five major distance records simultaneously since Shane Gould?

She has a chance.

We’re on the ground in Rio covering the 2016 Summer Olympics. Check out all our coverage here.