Ethan Kohler has come a long way since he first worked with Marko Mitrovic as a 17-year-old central midfielder at a U.S. U-19 camp.

He departed the camp with a list of eight to ten things to work on, including the direction of his first touch, cleaner passes, and better anticipation.

"I was not called back into a camp for two years," Kohler recalled.

He took the feedback seriously. Three years later, he played center back for Mitrovic at the 2025 U-20 World Cup in Chile. He started four games, collecting 3-0 wins over France and Italy.

It was a product of his commitment to improve, a trait he still has today.

"You have players that are going to take [feedback] very seriously and work on it," Mitrovic said. "You have players that are going to be very motivated but for a very short period of time. You might have a group of players that are never going to take that advice seriously.

"Ethan is one of those guys that takes everything so serious, and his mindset is just amazing."

Kohler and Mitrovic are now working together at the New England Revolution. The 21-year-old featured as a right back and central midfielder before settling in as a center back.

A tenacious defender, Kohler ranks fifth among defenders in aerial duels won (79.2%) since Major League Soccer play resumed on July 16 (minimum of 20 aerial duels).

He can also create, completing 95.8% of his passes, the best in MLS among those with at least 1,300 minutes. He earned his first league assist in Saturday's win over Orlando City SC.

His confidence on the ball makes him a perfect fit for the Revolution's style.

"[Kohler] is a very good player on and off the ball as well," Daniel Gazdag said. "He can play different positions, and I think the most important [thing] is that everyone is confident on the ball, which helps if somebody is in trouble on the field. [Then] everyone else is showing up and trying to get the ball and help each other. I think that's really important."

While he obviously appreciates Kohler's on-field ability, Mitrovic is quick to recognize his general disposition.

"It’s not just about him and his development, Ethan is also highly a team player," Mitrovic said. "He is not just aware of himself, but also of the team, how our team can get better, and what our standard is.

"Ethan is one of those guys that actually keeps our standards high coming into this environment every day."

Becoming a full-time starter in MLS is a huge milestone for Kohler, especially after a turbulent three years in Germany where he played for Werder Bremen’s U-19s, Werder Bremen II, and SC Verl.

Of course, he still has more to accomplish, and Mitrovic knows that Kohler will do everything in his power to achieve those goals.

"I have only great things to say about Ethan," Mitrovic said. "I’m not worried about saying that because, knowing his mentality, great words about him are not going to put him in sleep mode because Ethan is who he is and he’ll just keep going."