Eleven of the 23 players on the U.S. World Cup roster are with European clubs this season, and just four have been regular selections.
Tim Howard (Everton) and Brad Guzan (Aston Villa) are their club's top goalkeepers in the Premier League. Midfielder Mix Diskerud worked his way back into the starting lineup of Norway's Rosenborg by late summer, and midfielder Alejandro Bedoya has started seven of Nantes' first nine Ligue 1 games.
Two defenders have seen some playing time in Germany. Fabian Johnson, who missed the U.S. exhibitions in the past week because of an Achilles tendon injury, has made four starts and two substitute appearances in the first seven Bundesliga games of his new club, Borussia Moenchengladbach.
Defender Timothy Chandler, in his first season with Eintracht Frankfurt, has made three league starts and two substitute appearances.
After that, there's a huge drop-off.
"For MLS players it's a bit easier to go back in their environment, because they are kind of stars in their teams.
They are not really in doubt there," Klinsmann said. "In Europe it's a different ballgame."
Injuries have contributed to decreased playing time.
Forward Aron Johannsson scored 26 goals for AZ Alkmaar last season but hasn't played this season due to ankle surgery in July and a groin injury last month.
Defender and midfielder Geoff Cameron, who appeared in all but one of Stoke's Premier League games last year, has made just one appearance for the Potters this season, leaving a League Cup match on Aug. 27 in the 37th minute. He hasn't played following hernia surgery.
Julian Green, the 19-year-old who scored in overtime in the second-round World Cup loss to Belgium, was loaned from Bayern Munich to Hamburg and made his Bundesliga debut on Sept. 14, when he played the first half at Hannover. He entered as a 75th-minute sub against Bayern six days later and injured a rib, causing him to miss the games against Ecuador and Honduras.
But some are just plain struggling to break through.
Defender John Brooks, who scored the go-ahead goal in the Americans' World Cup opener against Ghana, made three starts for Hertha Berlin in late August and September, then was demoted to Hertha's under-23 team.
"They know how much quality he brings to the table, but in his position they're loaded with four, five guys. So they give him a little signal," Klinsmann said. "He also has to learn to deal with those moments, not having the feeling 'I'm guaranteed here.' ... Not in Europe. So that's what they teach him right now."