At the conclusion of the 2011 Gold Cup, the USMNT was in a bit of a mess. Bob Bradley had a reasonably successful World Cup, before taking his squad into the Gold Cup final where they were outclassed by Mexico. This is where Klinsmann was brought in, and this is what the team he inherited looked like.
There are a lot of problems here, specifically in defense. Bradley decided to come out with a lineup that could potentially compete with Mexico to hold possession and the midfield battle. While that failed, the team was able to take an early 2-0 lead through the play from Dempsey, Donovan, Bradley and Freddy Adu (!!!!) (Altidore missed out due to injury). From there, the defense fell apart (specifically after Cherundolo was replaced by Jonathan Bornstein due to an early injury). What's more, the line up (and, indeed, the entire squad) was stacked with aging or ineffective players that Bradley depended upon, especially in defense.
Klinsmann came in with a mandate to do a few things. The first was to reform the US soccer federation to become a more efficient producer of talent (a role that is WAY beyond the scope of one person, though there have been improvements here, including from Klinsmann). Second, he was to instill a culture where the USMNT played with a sophisticated tactical and technical mindset that was imposed on the opposition (this was thrown out almost immediately and has been revisited only in a handful of friendlies). And finally, Klinsmann had to manage the USMNT in a fairly successful manner. This last part is the only one relevant at this point.
When Klinsmann came in, he had to identify the aging and ineffective parts of the USMNT and replace them with younger, more effective players that he had identified and recruited. This last part was not as easy as it appeared. Take a look at this set of paragraphs from SB Nation's own analysis following the Gold Cup final loss.
The biggest problem that the United States has is in the center of defense, where all of the established options are either on the downside of their careers or perpetually average. Carlos Bocanegra, Jay DeMerit, Oguchi Onyewu and Clarence Goodson all fall into that category. With the current young crop of American central defenders having a good deal of natural talent and almost no big game experience between them, it would be seriously hindering to both the long-term and short-term future of the U.S. men's national team to have more than one of these players in the squad at any given time.
United States fans can engage in endless debates about whether Tim Ream, Ike Opara, Gale Agbossumonde, Omar Gonzalez, or Ethan White is the next great American central defender. What they can all agree on as a group, though, as that at least two of those players (or similarly young players) are going to have to be in every single squad from here on out.
The analysis is absolutely right in pointing out who needs to be replaced in the squad (though that could be expanded to include the fullbacks like Cherundolo and Bornstein.) However, it almost completely misses the mark on who would end up a part of the national team under Klinsmann. With just one exception, none of these players has reached a level where they became mainstay starters. Even in Gonzalez's case, he was the third or fourth string starter by the World Cup, and, depending on form and whom you ask, is somewhere between third and sixth in line at center back. The others have become serviceable MLS players, Championship mainstays, or USL starters. Instead, we saw the emergence of Geoff Cameron and Matt Besler, followed by John Brooks.
Now, it's not necessarily because of Klinsmann that these players became skilled international players while the others didn't. For one reason or another, Besler, Cameron, and Brooks developed and gained form while the others saw their careers go elsewhere. Klinsmann merely reacted to those developments and picked the qualified individuals. But there are other examples where Klinsmann WAS able to find talent that was otherwise not considered or discarded. Kyle Beckerman and DaMarcus Beasley are the best examples.
Beckerman is roundly criticized now for, essentially, having aged. But his ability to pass and take up strong defensive positions has been vital for years, first with Real Salt Lake, and then in Klinsmann's early term. DaMarcus Beasley was essentially done with the national team under Bradley, with his decline due to age. Klinsmann was able to identify both of these players and figure out exactly how to make the most use out of them such that they benefited the whole team. However, Klinsmann not only figured out who would benefit the national team and how, but he was able to transition the team into a new one by dropping old and poorly performing players. Klinsmann made room for the new center backs by dropping the old ones, sometimes fairly ruthlessly. I remember the shock from hearing that Bocanegra was essentially done with the national team, but it was a gamble that paid off big for Klinsmann. He was able to drop aging players, find players who fit, and integrate them into the squad.
Klinsmann still does a good job at identifying talent. He's been a fantastic recruiter, picking up a host of different dual nationals, including Julian Green, Darlington Nagbe, Aron Johansson, and, perhaps most importantly, Fabian Johnson. Klinsmann was able to identify Bobby Wood as a player with a bright future, even as the rest of us shrugged and complained. Klinsmann found Jordan Morris when he was a college player, and not even an especially renowned one at that.
Klinsmann has done an excellent job and finding players who can eventually perform for the national team. But now, he's struggling to remove the aging and ineffective ones. Timothy Chandler. Michael Orozco. Kyle Beckerman. These faces keep getting call ups and caps even though they are not performing. And this means other, better and/or younger players are being excluded or kept on the bench. Jordan Morris didn't go to the Copa America because Klinsmann chose Wondolowski instead. In the two most recent qualifying matches, Klinsmann played Jones (who is coming back from injury and has never played well with Michael Bradley in a two midfield set up) over the in-form Kljestan, excluding Nagbe all together. You could even point out that the only reason why both Wood and Pulisic are getting time is because Dempsey, who is 33, is out.
The other major issue is in defensive solidity. In the early part of Klinsmann's tenure, he got the team to play a reactive and defensive style very effectively. It may have been ugly soccer, entirely reliant on parking the bus, but it worked. Klinsmann somehow was able to entirely transition the backline in a few years, all while eking out low-scoring results. The US went to Italy and was able to 1-0. We beat Mexico 1-0 in Mexico for the first time, before managing a scoreless draw in World Cup qualifying in the same venue a year later. We beat Ghana on the third attempt by a single goal. At one point, the USMNT won 15 out of 16 matches, including a 12 straight series of victories. In the first 6 rivalry matches against Mexico under Klinsmann in all competitions, the USMNT went undefeated and registered a 3-0-3 record. That is a really impressive body of work.
However, in the past 2 years, the USMNT has struggled defensively. We lost to Guatemala by 2 goals for the first time in history. We lost to Mexico in World Cup qualifying, breaking both the 2-0 record in Columbus, and the 15 or so year streak of not losing a home qualifying match. We got scored on by minnows like Puerto Rico, St. Vincent and the Grenadines, and New Zealand. This stems from Klinsmann's tinkering with the backline, while giving varying instructions to the rest of the team. The exception to this was during the Copa America, when Klinsmann decided to start Cameron and Brooks together for a string of matches. Thanks to that decision, the team was able to hold at least a semblance of defensive cohesiveness through enough of the Copa to reach the semifinals. And at that point, the defensive frailty was made completely obvious. Before the qualifying matches, Cameron went out injured. Klinsmann, for whatever reason, responded by playing a brand new formation with players in new positions. This tinkering has caused the team to be incredibly inconsistent and fraught in defense. And it could be simply corrected by Klinsmann returning back to consistency in his tactics and player choices.
Look, Klinsmann ought to be sacked. I think he ought to have been sacked back when he lost to Mexico in the Confederation's Cup qualifier. As a new manager, Klinsmann showed ability and skill in bringing in and integrating new players and using consistency to get results. He's not succeeding at either of those things, and, because of that, the team is in a bad position for qualification and has suffered a big loss in reputation. Those issues need to be corrected and it's been apparent for a long time that Klinsmann's too entrenched to make that happen.