Missy Franklin competes in the 100-meter backstroke prelimary heat Monday. (Jonathan Newton/The Washington Post)

Since becoming the swimming darling of the 2012 London Olympics at age 17, when she won four gold medals and melted hearts with her bubbly personality and constant smile, Missy Franklin has injured her back, left her coach, entered college, left college, turned professional and reunited with her coach — all the while watching her times decline in most of her core events and seeing her crown as the unquestioned queen of American swimming snatched away by Katie Ledecky.

And now, as the U.S. Olympic swimming trials approach their halfway point, a brutal new reality confronts her, as well as Team USA: Entering Wednesday night’s final of the 200-meter freestyle, Franklin, still just 21, was not guaranteed a spot on the U.S. team for the Rio de Janeiro Olympics in August. And unless there is a significant change in direction the rest of this meet, she likely won’t regain her London form in time for Rio.

The change in Franklin is visible both in the water, where she finished a distant seventh in the 100-meter backstroke Tuesday night — an event in which she won gold in London — and out, where her smile appears forced, a mask that hides a head full of frustration and angst.

“I think I’m dealing with more pressure than I’ve ever had before. But that’s part of the process — learning how to deal with it and how to move forward,” Franklin said following that 100 back final, in which she lost to Olivia Smoliga in a time, 1:00.24, that was nearly two seconds off of her personal best. “I had a race strategy. I went out and I did it, and it just wasn’t good enough this time.”

Said Todd Schmitz, Franklin’s coach with the Colorado Stars: “Is she disappointed? Of course she is. But being disappointed and using that to motivate you is different than being disappointed and just sulking around. On this pool deck, you see a lot of both. We can’t go back and swim them again. We just need to move on. . . . That’s why they swim the races. Swimming is a fickle thing, and it does it crazy things sometimes.”

Franklin remains the most marketable female swimmer in the United States, particularly with Ledecky choosing to remain an amateur after Rio and swim for Stanford. Franklin’s image is everywhere at Olympic trials — adorning the entry doors of the CenturyLink Center and popping up frequently in promotional videos on the giant video boards above the pool. There is perhaps no more universally beloved swimmer in America.

“Your heart breaks for her,” Team USA women’s head coach David Marsh said. “That’s all I can say. I’m heartbroken for her going through this. [But] I have a feeling if we can get her where we need to get her, in about four weeks [in Rio] she’s going to be way faster.”

So, to ask the question on everyone’s minds in Omaha: What is wrong with Franklin? She insists her back — which suffered a crippling bout of spasms at the 2014 Pan Pacific Championships — is fine. But it still flares up occasionally, and more glaringly, the injury is also an obvious line of demarcation in her career: She hasn’t been the same since it first happened, with no victories in major international meets and no personal bests since 2014.

Others have speculated that her two-year split from Schmitz, during which she swam for the University of California, and her subsequent decision to leave school and come back to him last year, amounted to simply too much change to endure in one Olympic quadrennial. It is also no secret that Franklin’s many sponsor and media obligations since turning pro spread her thin during some of the most critical training periods ahead of trials. Many times Schmitz would fly with her to those appearances, securing pool time for them at a local spot, then fend off crowds of gawkers who wanted to watch her train.

“I thought I would have a really good handle, going into it,” Franklin acknowledged of her scheduling obligations at a meet in Mesa, Ariz. in April. “I kind of had a couple years to prepare for it, which I felt was an advantage. [But] it definitely is a little bit more tiring than I was expecting it to be.”

In one particularly busy stretch, Franklin flew from Denver to Phoenix for a USA Swimming appearance the week before the Mesa meet, then back to Denver for a few more days of training, then back to Arizona for the Mesa meet, then from Mesa to New York for a Speedo appearance, then back west to her Denver base to resume training. More than 6,000 air miles logged in a little more than a week.

“If I could dictate more things as the coach, I would’ve said, ‘Man, that’s probably not ideal,’ ” Schmitz said. “But at the end of day, I have to pick my battles. Since the middle of May, we’ve been in sponsor and media blackout.”

Marsh said Franklin may be suffering for her innate need “to please everybody.”

“I’m glad none of my [club] swimmers has their pictures on the video board every time they walk in the pool for every single session,” Marsh said. “I feel for her, and I think we’ve all felt for her the whole time. It’s a hard transition becoming a professional, and especially with the kind of person she is. . . . She doesn’t let her guard down very well.”

Franklin is known as one of the most relentlessly positive athletes in any sport, but this meet has taxed even those prodigious powers. The slivers of remaining optimisim are twofold: Wednesday night’s final of the 200 free, which was expected to be dominated by Ledecky but where even a fourth-place finish would earn Franklin a spot on the 4x200 freestyle relay in Rio — and thus remove the pressure of simply making the Olympic team. And then the 200 backstroke, the race that remains Franklin’s best, on Friday and Saturday.

The goal in the 200 free final, Schmitz said, “is to punch her ticket.” Where others see slow starts and poor underwater technique, Schmitz sees her making up ground at the end of her races, which he figures bodes well for her 200 back.

“The endurance is there. She’s finishing like a champ,” he said. “And every one of her races, she was still barreling down the field.”

As difficult as it is to see one of the most decorated 2012 American Olympians struggling just to make the team in a relay, that is Franklin’s new reality. Perhaps if she can do that, the pressure will be lifted, and she can pour herself into the 200 backstroke without facing the dark possibility of being shut out completely.

“Right now,” Franklin said Tuesday night, “I just need to make the team, in whatever way.”