Garber held a media conference call Wednesday to chastise Klinsmann for a comment earlier this week about Bradley, who left Roma for Toronto this season, and Seattle Sounders striker Clint Dempsey, who quit Tottenham for MLS.
"It’s going to be very difficult to keep the same level that they experienced at the places where they were," Klinsmann said Monday. "It's just reality. It's just being honest."
The U.S. coach also said Bradley, after a frustrating season in Toronto that seems destined to end before the playoffs begin, "has to prove that he hasn't lost a bit."
Garber said such comments were plain wrong, not to mention detrimental to the league and the athletes. And he tore a strip off Klinsmann for using such a public platform.
"We're dealing with young professional athletes," said Garber, who went on the offensive Wednesday. "I don't know what possibly could have motivated Juergen to so publicly criticize Michael Bradley and ultimately Clint. It is concerning to me that it seems to be following a pattern that began with his criticism of Landon (Donovan)."
The 32-year-old Donovan, the career scoring leader for the national team and MLS, was cut by Klinsmann in May in advance of a fourth World Cup.
"I believe that Landon should have been in Brazil, not because he earned it or deserved it, but because his performance dictated it," Garber said. "And if anybody disagrees with that, and some of you might — clearly Juergen does — then I believe that his treatment was inexcusable.
"And I have concerns that his criticism particularly of Michael is following that same pattern."
Garber said Klinsmann's comments about MLS were incorrect and "incredibly damaging" to the league as well as at odds with what MLS and U.S. Soccer were trying to achieve together. Klinsmann is also technical director of U.S. Soccer.
"For him to publicly state issues that he has with Major League Soccer, in my view is not something that is going to allow him to effectively serve the role as not just coach but as technical director," Garber said. "I am in no way saying what Sunil (Gulati, president of the U.S. Soccer Federation) should be doing with Juergen as it relates with his employment. That is between Sunil and Juergen.
"I think he's done a great job with the national team. I think he needs to think very, very hard about how he manages himself publicly and how he deals with his view as to how he should motivate players that are playing in our league."
Ten members of the U.S. World Cup squad this summer play in MLS, with another five having started in the North American league, the commissioner noted.
"Sending a negative message to any player, and obviously to U.S. players, that signing with Major League Soccer is not going to be good for their career or good for their form is incredibly detrimental to Major League Soccer," said Garber.
He pointed to Seattle defender DeAndre Yedlin's upcoming move to Spurs as proof that playing in the North American league does not negatively impact form.
Garber said MLS franchises in both the U.S. and Canada were developing homegrown talent for their national teams.
As such, Garber said having the U.S. coach not on board is "frustrating as hell."
Klinsmann, a former star striker who coached Germany, called Bradley's decision to leave Roma, which is playing Champions League football, for Toronto "a huge disappointment."
Bradley, speaking to ESPN FC, disagreed with Klinsmann that players need to be in Europe's elite leagues.
"You can be in a fantastic environment but if you don't put everything into it and think you've already made it or that there's no need for extra work, you have no chance," Bradley said prior to the U.S. game against Honduras on Tuesday in Boca Raton, Fla.
"On the flip side, you can be in what some would call a less-than-ideal environment, but if your hunger and determination and drive push you to walk on the field every day ready to do everything possible to compete, help the guys around you and be a better leader, you'll improve."
Garber said Bradley, who has won 91 caps for the U.S., would not have come back to MLS "if he did not believe that it was in is competitive best interest to do so. And I could assure you that Clint Dempsey feels that way.
"And nobody was saying that Major League Soccer was unworthy when Clint scored two great goals including a game-changing goal against Ghana in the Word Cup."
Garber said he had sent a "very strongly worded letter" to Gulati, adding some MLS board members had done the same unsolicited.
He also said he had written to Klinsmann but had yet to speak to him.
Garber declined to say whether Toronto and Seattle had complained to U.S. Soccer. Toronto FC did not immediately respond to a question about whether they had complained about Klinsmann's comments.
Asked Tuesday about Klinsmann's comments, Toronto FC coach Greg Vanney shook his head.
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