Do you consider Ryan Leaf a failure? How about JaMarcus Russell? Both of them were starters in the NFL, which is more than 99.blahblah% of football players can say.
Failure is always relative to expectations. Yes, the woman who finished last in the first Olympic prelim still had a remarkable achievement in simply making it there. And yes, even the woman who finished last place in the final is faster than anyone any of us will ever know.
But Lolo Jones was not expected to finish fourth.
She was expected to win, or at the very least, medal. And she did neither, which is a failure.*
If Michael Phelps had finished this Olympics holding a pair of bronze medals, that also would have been a "failure." And yet, there are plenty of other Olympians on Team USA for whom two bronzes would be an incredibly amazing achievement. Expectations matter.
*edit: Actually, I have to take most of this post back. Apparently, Lolo Jones wasn't
really expected to do anything at all (
link), and has essentially been elevated to Kournikova/Tebow-status by the media. So I guess she isn't really a failure if she was being overrated from the start.