He's got 156 caps, 57 international goals and has scored as often at World Cups as Ballon d’Or winners Lionel Messi and Cristiano Ronaldo combined. Impressive stats, but not those of a man whose team is tipped for World Cup glory: they describe the USA's all-time best player Landon Donovan.

When the US team manager Jurgen Klinsmann excluded him from the final list of players heading to Brazil 2014, most football fans in the States were furious and many are still in shock.

A tweet from Klinsmann’s son Jonathan riled fans by laughing at Donovan. The coach's kid was soon hounded off Twitter but it announced open season on the golden boy and the start of the conspiracy theories.

The exclusion is perhaps an even bigger shock than in 1998, when coach Steve Sampson left captain John Harkes out of the World Cup squad after the midfielder had an affair with team-mate Eric Wynalda's wife (Wynalda and Sampson revealed this in 2010, although Harkes still refused to confirm it).

Klinsi and Donovan: a history

Ask the American average-Joe to name soccer players and they may mention Pele's time at the New York Cosmos, even if they never saw him play, and David Beckham, especially if their Average Josephine is a fan of the Englishman’s looks. Next on the list, a good percentage will name Donovan. They remember his goal against Algeria in 2010 that not only won the game but sent the US through as group winners.

Donovan’s omission was an audacious move that no American coach would have made. But Klinsmann’s decision did not start last week. A major turning event in the past with a player he once trusted led to this move.

In 2009, when he managed Bayern Munich, Klinsmann brought Donovan over for a loan during the MLS's winter close season. The American’s performances were below par, the Bavarian bigwigs didn't extend his loan and a few months later Klinsmann was out too.

In August 2011, Klinsmann took over Team USA, and Donovan was the player he knew best. But as the coach prepared for the crucial World Cup qualifiers in February and March 2013, the star player absented himself, choosing instead to extend his sabbatical to Cambodia. While Donovan was "finding himself" in the south Asian jungle, his team were struggling to find a way to Brazil, losing 2-1 to Honduras, squeaking past Costa Rica 1-0 and managing a goalless draw in Mexico.

With ageing captain Carlos Bocanegra drifting out of the first XI, many had expected Donovan to take the armband. Instead, Klinsmann anointed Clint Dempsey, who scored both the American goals in those spring fixtures. A year later, Donovan had gone from expected next captain to squad outcast – but the signs had been there.

In an ESPN documentary airing before the release of the squad list, Klinsmann had been perfectly plain about Donovan's position, only partially clothing his quotes in deference to the player's history. “The media thinks he’s untouchable," said the coach. "The media thinks he has to be in the starting line up or he has to be in Brazil based on what he did for soccer in the United States over the last 12-14 years, but that’s not how it works.”

Having been hurt twice before, Klinsmann had made clear to Donovan the need to apply himself consistently. But in the same documentary, the player openly spoke about his inability to inspire himself to train harder.

“Sometimes it’s a bit difficult for me. I can’t train 12 straight days in a row and have 12 straight great days," admitted Donovan, before apparently acknowledging that he could force Klinsmann into a tough decision: "If he sees me perform poorly for three straight days, he has to make the choice to play someone else.”

Changing of the guard

Regardless of what most Americans think of Klinsmann’s managerial CV, he was a very accomplished player and is still competitive to the point of argument: he recently complained about the dearth of American players plying their trade with top European clubs.

Meanwhile, Donovan has long had his unimpeachable status revoked. In a key qualifier at home to Jamaica last October, Klinsmann was unimpressed by his No.10's level of competitiveness during a goalless first half; unlike any previous American manager, the German subbed him for Graham Zusi, who went on to score the first in a 2-0 win.

The second goal was scored by Jozy Altidore, whose season at Sunderland has been disappointing to say the least. But Klinsmann has been protective of Altidore and other less-fêted players.

On the plane to Brazil is the teenage Julian Green, a once indecisive defender (Timothy Chandler) who was unsure of his allegiance to Germany or USA, and a handful inexperienced centre-backs, one of whom (Omar Gonzalez) has been condemned for poor positioning. One can only assume the manager wanted to go with players who work within his system and appear eager in training to impress and improve.

Unlike goalkeepers, defenders and wine, forwards tend not to get better with age. Now 32, Donovan has been known for his speed and it is inevitable that he would lose that edge. In what now looks like a final warning, for April's friendly against Mexico – the last game before the naming of the World Cup squad – Donovan was dropped from the starting XI; when he did appear in the second half, he seemed out of shape and easily stopped by the hardly rapid Rafa Marquez.

In that game, the US had shot into a 2-0 half-time lead through attacking midfielder Michael Bradley and striker Chris Wondolowski, playing up top alongside Dempsey; Donovan was merely one of six replacements brought on in the second half as Mexico fought back to 2-2. No longer first choice, the former star was apparently now struggling to justify a place at all.

Klinsmann was watching everything transpire and obviously saw something he did not like. Only coaches know why they make certain tough evaluations; we can speculate on what was the right move, but it had to be made and no one else could have other than Klinsmann.