Aaron Peirsol hadn't lost the 100-meter backstroke at a major competition in eight years. This time around, he didn't even qualify for the finals.

In the most stunning result so far at the World Swimming Championships, the man who some call the greatest backstroker in history failed to qualify for the 100 back final after finishing with the 9th best time among two semifinal heats. Peirsol finished in a 53.22, one-tenth out of the final and 1.28 seconds slower than the world record time he set earlier this month.

Peirsol said he "completely misjudged" where he was in the race, suggesting that his 9th place finish was more the result of strategy rather than ability. And, indeed, he did seem to lay back a little too much in the final 25 meters (where he usually thrives).

But Peirsol is good enough to compensate for a poorly-executed swim. Even a poor race should get him into the finals. So what happened? As has been the case for the last 12 months, it all comes back to the swimsuit.

It's not so much that Peirsol's swimsuit caused him to go slower (although he was only one of the three semifinalists to not wear an over-the-shoulder suit), but that other competitors have improved so much because of their polyurethane-based suit that they've been able to play catch-up, despite not having as much speed.

FINA thankfully banned those suits starting in 2010, but they're having a last hurrah at worlds and, in turn, making a mockery of swimming. (Check back to Fourth-Place Medal later today for more about the impact of the suits at the world championships.)

Before her post-race interview with Peirsol, NBC's Andrea Kramer could be overhear asking the five-time gold medalist whether he wanted to talk about his suit. Ever cool, even in defeat, Peirsol declined.