Dave Sarachan spent 3 1/2 years as an assistant with the U.S. national team and 14 seasons coaching in Major League Soccer. So he knows a thing or two about the difference in play at those levels.
"It's like going from a basic level of math to trigonometry," the Galaxy assistant said. "It's deeper. There's more going on. And there's an adjustment period to all of that."
That's the period Gyasi Zardes finds himself in now, a month into his first call-up to the senior national team.
"It's been a challenge," the Galaxy forward said. "It's fast. Boom, boom, boom.
"I'm just trying to learn as much as I can."
But if Zardes is taking some positive lessons away from his first training camp, which ends with Sunday afternoon's friendly against Panama at the StubHub Center, he's also leaving behind a positive impression.
"He confirmed what we saw. That he's a very, very talented forward," U.S. Coach Juergen Klinsmann said. "And knowing him a bit more on the personal side, he's very teachable. He's eager to improve. He's hungry.
"It's really fun to work with Gyasi. He deserves to be part of this group."
In fact, he may eventually prove to be an indispensable part of the group.
Fast yet tough at 6 feet 2 and 175 pounds, Zardes comes from the same mold as Jozy Altidore, whose 13 goals since 2012 leads all U.S. players. He also has the same exceptional instincts. So even when he doesn't have the ball, he works himself into dangerous spots, as he did repeatedly in his national team debut 12 days ago, when he came on for Clint Dempsey in the 68th minute of a 3-2 loss to Chile.
"What we lack in the national team pool is a physical presence up top. Outside of Jozy, there aren't any," said Sarachan, an assistant coach for the U.S. team that reached the World Cup quarterfinals in 2002. "Now you've got a guy like Gyasi. He's got the ability to have that kind of a presence where he's a handful for defenders. And that's what this national team pool needs."
Well, that and a strong second half. The U.S. goes into Sunday's game riding its first five-game winless streak since 2007 and with just one win in nine tries since beating Ghana in last summer's World Cup opener.
But wait, it gets worse. Because in their last eight games, the Americans have been outscored 12-1 after halftime. And in their last eight winless games, they've let a tie or a lead get away in the second half.
Klinsmann is desperate to stop that slide against Panama, if for no other reason than to reward his players at the end of an exhausting camp.
"You want them to get a positive result. You want them to kind of say, 'This was a lot of work that we put in here, let's get three points'," he said. "Even if we know it's a preseason, friendly game … we want them to pick up on that importance of an international game to get the results they deserve."
Breaking camp on a high note may be even more important for young, impressionable players such as Wil Trapp and Steve Birnbaum who, like Zardes, also earned their first international caps against Chile. It was Zardes who arguably had the best debut, though, impressing with both his head and his heart.
"His mind is in the game," Klinsmann said of Zardes, who has a well-earned reputation of being a tireless worker. "He makes runs where maybe other people wouldn't. He wants to make himself available.
"The ball drops and [he says] 'I'm going to be there'. That is nice to see. Also for him, it seems like making those runs is no big deal."
Running, after all, is one reason that Zardes chose soccer over football coming out of Lawndale's Leuzinger High. One of the state's top prep placekickers, he turned down football offers from Penn State, Oregon State and Boise State to play soccer at Cal State Bakersfield, where he had to work part time at a Jamba Juice to make ends meet.
He also put the squeeze on opposing defenses there, scoring 33 times in his final 37 college games to lead Bakersfield to the NCAA tournament for the first time in school history, while becoming a semifinalist for the Hermann Trophy, soccer's version of the Heisman.
The Galaxy signed Zardes, a product of its youth academy, as a homegrown player in December 2012, and four months later he made his MLS debut. Two games after that he scored his first professional goal.
He enjoyed a breakout year in 2014, ranking sixth in the league with 16 goals in 26 starts before capping the season with the Galaxy's first score in their overtime win against New England in the MLS Cup Final.
Given Zardes' quick success, Sarachan said the humbling step up to the national team couldn't have come at a better time for the 23-year-old.
"It's the speed. It's the physicality. But it's also the pressure. Going into environments that are pressure cookers is a big part of the process," the Galaxy assistant said. "The moments that come require a higher level of concentration and speed of thought and ideas.
And now Zardes is changing with them.