RIO de JANEIRO — Coming into these Rio Olympics, after the U.S. team’s underwhelming performance at the 2015 World Championships, there were concerns far and wide about how the American swim team might do at the 2016 Rio Games.

Watch fans and athletes react to the end of an era when Michael Phelps retires. 

Now the answer is as plain as #PhelpsFace.

The 2016 U.S. swim team was, in a word, riveting.

Just excellent.

With the two open water swims still upcoming, the U.S. swim team’s 2016 medals count stands at 33.

In London four years ago, the U.S. team won 31 medals, 30 at the pool (Haley Anderson took silver in the women’s open-water swim). In Beijing, 31 (all pool, no medals in the first-ever Olympic open water swims). In Athens in 2004, 28.

In Sydney in 2000, at the start of the Michael Phelps years, the then-15-year-old taking fifth in the men’s 200m butterfly, the U.S. team won — 33.

Talk about full circle.

After Rio, Phelps’ medal haul is so titanic there really are no superlatives: 23 gold, three silver, two bronze.

This is a good thing, of course. USA Swimming is, first and foremost, in the business of winning Olympic medals.

In Rio, the Americans won 16 gold medals; the rest of the world, 17.

These counts fully reflect the way USA Swimming has not only raised the bar but been able to sustain its competitive edge over the years — in no small measure thanks to Phelps.

At the same time, the numbers also raise fascinating questions about the state of the sport — which, after all, has to carry on for more than the eight days every four years that it gets prime-time television love.

Where does swimming go from here if — as he has declared numerous times here — Phelps is, for real, done?

Whether he is done, or should be, is a separate matter entirely.

To be frank, Phelps could take two and a half years off, put in 18 months of work (maybe even less) and still very likely win — or, at least, take a medal in — the Tokyo 200m IM. His nearly two-second victory here shows, one, how good he is at it (in particular, how much his third leg, the breaststroke has improved) and, two, how far ahead of everyone else in the world he is.

If he were to come back in four years for the 200m IM and, oh, make himself available for the relays — do you think that might be a win-win-win for Phelps, USA Swimming and the Olympic scene?

Phelps has long said his goal is to grow the sport.

Here’s evidence of progress:

Tuesday’s instant classics at the pool — Phelps’ historic victory in the men’s 200m butterfly, Katie Ledecky’s soulful win in the women’s 200m freestyle, the U.S. men’s victory in the 4x200m freestyle relay — got the full prime-time treatment.

So, too, Friday’s bang-bang can-you-believe that, and that, and that? And, finally, that?

Maya DiRado winning the women’s 200m backstroke; Phelps in a three-way tie for second in the men’s 100m fly behind Singapore’s 21-year-old Joe Schooling; Katie Ledecky going an otherworldly 8:04.79 to nail down the women’s 800m free after earlier wins in the 200m and 400m freestyles; and, then, 35-year-old Anthony Ervin winning the men’s 50m free in 21.4, 16 years after — at those Sydney Games — he and Gary Hall Jr. tied for gold, in 21.98 seconds.

On Saturday, the medals kept coming;

Simone Manuel followed up her meaningful victory in the women’s 100m free with a 50m free silver, then anchored the U.S. women’s medley to victory in 3:53.13; Connor Jaeger took silver in the men’s 1500m free; and the U.S. men, with Phelps pulling the third split in the fly and Nathan Adrian anchoring, winning gold in the medley relay, in an Olympic-record 3:27.95.

The women’s medley medal marked the 1,000th Summer Games gold for the United States in modern Olympic history, dating to 1896. The men’s: 1,001.

More evidence:

At the Baltimore Ravens’ first pre-season home game on Thursday, the football literally came to a stop for roughly two minutes to air Phelps’ winning performance in the 200m IM over the stadium big screens. The crowd went crazy for its hometown guy.

At the Washington Nationals baseball game Friday, the team replayed the final stages of Ledecky’s world-record 800m on the video scoreboard during the seventh-inning stretch.

More still:

More nations are swimming, and more nations are producing elite athletes.

When he was little kid, like a lot of little kids, Schooling took a picture with Phelps.

Schooling, with one gold medal to Phelps’ 23, now has lifetime do-you-know-what-I-did rights.

Five of the others in the eight-man 200 fly final got their start because of Phelps, including South Africa’s Chad le Clos, who memorably defeated Phelps in the London 2012 200m fly by five-hundredths of a second and who — along with Hungary’s Laszlo Cseh — made up the Rio second-place 100m fly three-way.

And yet more:

The Rio 2016 pool has seen world records in events as varied as the women’s 400m and 800 frees (Ledecky), men’s 100m breaststroke (Britain’s Adam Peaty), women’s 100 fly (Sweden’s Sarah Sjostrom) and men’s 100 backstroke (American Ryan Murphy, leading off Saturday’s medley).

All good.

If the focus is only the Olympics.

What to say, really, about the FINA world championships, which are the premier event in odd-numbered years? The Pan Pacific championships, which are held in the even-numbered year between Olympics?

Do they matter?

Or, more precisely: how much do they matter?

Or, better yet: is it only the Olympics that really matter?

Because of Phelps, swimming is now what the International Olympic Committee considers an “A”-level sport for funding, along with gymnastics and track and field.

But Sunday morning, as the Olympic spotlight turns to track and field, swimming is nominally Phelps-less.

And then what?

Replacing Phelps is just one order on the table for USA Swimming. It is now — if not soon enough — going to be looking at a future without the legendary coach Jon Urbanchek, the father figure for an incredible number of Team USA athletes. And what of the next few years for the do-it-all Mike Unger, the federation’s No. 2, who makes so many things happen away from the spotlight?

Is the overall goal to compete with track and field for Olympic dominance?

Or, at least in the United States, to duke it out with the American professional leagues for attention — this means, yes, the NFL, NBA, baseball and NHL, even for goodness sake the lower-level soccer played in MLS?

Consider last year’s world championships, in Kazan, Russia.

At the 2015 Worlds, the Americans won only 20 medals in Olympic events. (Meaning, for instance, that Ledecky’s gold there in the women’s 1500m doesn’t count because there is no women’s 1500m, an anachronism, at the Olympics.)

That was down four from the 2013 Worlds in Barcelona.

It was in Barcelona that Ledecky, who had raced just one event at the 2012 London Games, winning gold in the women’s 800m free, announced to the world that she would be the next big thing: she set two world records in winning the 400m, 800m and 1500m freestyles while also swimming a leg on the victorious 4x200m free relay.

So there’s the argument that, clearly, the Worlds matter.

But to whom?

For sure a subset of athletes, coaches, officials and hard-core swim geeks.

But who else?

In Barcelona, for instance, Phelps was in the midst of his post-London “retirement.”

He was back by Kazan but didn’t swim there, out as part of the USA Swimming-mandated sanction following his second DUI incident.

Which, in and of itself, tells you everything you really need to know about what’s what.

If the Worlds were really just like the Olympics, Phelps would have been there. Bet on it.

Instead, Phelps swam at the U.S. nationals in San Antonio.

This is another clue. Organizers scheduled the nationals pretty much at the same exact time as the worlds. So athletes — with the exception of Phelps, forced to San Antonio — were either at one or the other.

USA Swimming “solved” this problem by picking the 2015 Worlds team from the results of the 2014 season.

Which, again, makes for compelling evidence that only one thing counts, really: the Olympics.

Where the Americans shine. Back to the pool now in four years — without Michael Phelps.

Maybe.

Here is your first over-under on a comeback: April 2019. Everybody check back then.

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