"During Caleb’s five seasons with our club, we reached new heights and accomplished great things together," said Timbers owner Merritt Paulson in a statement published on the team's website. "His commitment, passion and talent were essential in bringing many on-field successes to our supporters, our club and our city, most notably our first MLS Cup. More than that, he has been a friend whom I have enjoyed working with.
“I respect Caleb’s decision to seek his next challenge. He leaves Portland with a lasting legacy valued by everyone associated with the club, and I wish him nothing but success in the future.
Porter, who led the Timbers to the 2015 MLS Cup crown, also released a statement confirming his departure and thanking the organization and its fans.
“My goal in taking the Timbers job was to lead the club to new heights and to win things that had never been done by the organization,” Porter said in his statement. “Looking back and reflecting on my time with the Timbers, I am very proud of the results we all achieved and I know that joining the club in 2013 was one of the best decisions of my life."
Hired in 2013, the Timbers had a 68-50-52 record during his reign and made the postseason three of Porter's five seasons in charge, culminating in a 2015 MLS Cup triumph over the Columbus Crew for the organization's first MLS crown. Porter also won the MLS' Coach of the Year award in 2013.
In the two seasons prior to Porter's arrival, the Timbers did not make the postseason.
Before arriving in Portland, Porter was the head coach of the University of Akon, and managed the United States Under-23 side during a failed qualification for the 2012 Olympics in London.
He also led the Timbers to the semifinal of the 2013 U.S. Open Cup, and a quarterfinal appearance in the competition in 2014.
This season, the Timbers finished first in the Western Conference in 2017, the second time they accomplished that feat during Porter's tenure, but were eliminated by the Houston Dynamo 2-1 on aggregate in the semifinal round of the conference playoffs.