It's a matter of opinion, of course. But Top 10-15 is a pretty low bar. Think of many top 15 college football teams in the past several years. There have been some pretty crappy teams in there. Nebraska has more trouble scoring than the USMNT, and yet they were top 15 last year. Would you say CFB is in serious trouble?
Any sport - *any* sport - will have a large gap between the elite teams and the middle of the pack.
And the ranking is not based on just the World Cup, it is based on what you do as a National Team leading up to the World Cup. Your showings in qualification and some of the friendly matches will endorse your ranking (albeit, the friendly matches can be a big joke). But there are also pre-World Cup tournaments, like last year's Confederations Cup. The USA had a great showing at that tournament, it was the coming out party for Dempsey, Altidore and Bradley.
But just like, say, a Texas Longhorn basketball team being ranked number one during the pre-tournament phases of the season (re: regular season, when they beat such teams as Michigan State, et. al.) and then falling rapidly to a middle of the pack standing during March Madness tournament play, it can happen to a squad that the chemistry built during the qualifications and such will be lost if a organization does not realize they are messing with a good thing if they make mistakes picking their final squad to go to the World Cup.
In the end, the USA played great futbol at midfield most of the time, really horrid defensive futbol most of the time and so-so to disappointing futbol at the attack/finish positions. Altidore was shut down, many times by his own doing and that hurt. Findley was a mistake, plain and simple... he has no skills being a finisher (although he may develop that later in his career, but he was picked at the wrong time to be on the World Stage trying to be a finisher... he was piss poor). You cannot, in the end, show well against World Class teams in the final round of 16 unless you have all facets of the game working. Was it the players? I don't think so, not entirely at least. Bob Bradley has to look long and hard in the mirror, just like Bruce Arena did, and accept blame for his wild assumptions about some of his players performing on the the big stage. He had a chance had he stayed true to players skills, like a Feilharber and Edu over Clarke and Findley.
So while I agree 100% with Jurgen Klingsmen to an extent, I think it's time that a coach who has performed on the World Cup tournament takes over. If it's an American, then fine. If it's a former player from Europe, I'm cool with that too. It's time to make the American skills better at playing on the World Stage because they CAN do it. Now let's see if the strategy and poise can match the evolving skills of this squad. This World Cup proved that they are ready to move to the next step and become what all those fans who invested in them this time around were hoping for.