"It still hasn't hit me, but I woke up today super happy," Barea said. "It's been an amazing time here in Dallas. I wouldn't change anything.
"But it's a tough day. It's the end of me as a player in Dallas, but [I have] nothing but good memories."
The Mavs anticipated releasing Barea, 36, when they signed him to a one-year deal worth the veteran's minimum of $2.6 million last month. That gave the team 16 players with guaranteed contracts, one more than the regular-season roster limit.
Dallas owner Mark Cuban wanted to reward Barea, a key role player on the 2010-11 championship team who has played 11 of his 14 seasons with the Mavericks, for his contributions to the franchise.
"We've had an incredible, amazing ride with J.J.," Mavs president of basketball operations Donnie Nelson said. "He, in a lot of respects, has been the heart and soul for us for many, many years and certainly the pride of Puerto Rico. Today that comes to a close as we're forced to make cuts.
"I think with the fact that we're on a little bit of a younger direction, let's call it, with our backup point guard prospects, certainly the writing was on the wall. We all understood that coming in. I think it was really more of an appreciation for J.J. and the amazing things he's done in his career, why we brought him back as the 16th player on this roster and gave him a thank-you of sorts."
The move is expected to be made official after Thursday's practice, granting Barea's request to be released sooner than later if it was a certainty that he wouldn't be on the roster after final preseason cuts.
Barea remains determined to play in the NBA this season before retiring as a player and pursuing a career in coaching.
"J.J. has got a lot of juice left in the tank," Nelson said. "Anyone walking through that practice door will tell you he's still got it. He wants to add to his championship trophy case."
The 5-foot-10 Barea was productive in a limited role last season, when he came back from a ruptured Achilles tendon suffered in January 2019 to average 7.7 points, 3.9 assists and 15.5 minutes during his 29 appearances. He was considered a valuable leader despite not being a regular part of the rotation, mentoring superstar Luka Doncic and other young Mavs.
Barea made the Mavericks as an undrafted rookie in 2006 -- and began going by his initials because then-Dallas coach Avery Johnson often botched his given name, Jose Juan. Barea has career averages of 8.9 points and 3.9 assists per game, spending most of his career as a spark plug off the bench.
Barea's career is best remembered for his performance against the Miami Heat in the 2011 NBA Finals. With Dallas at a 2-1 deficit in the series, coach Rick Carlisle made a surprise adjustment to start Barea alongside Jason Kidd in the backcourt. Barea averaged 13.3 points and 4.7 points as the Mavs won the next three games to clinch the franchise's first championship.
"J.J. was as important a piece of a championship run as anyone," Nelson said. "His championship ring should have been a little bit bigger because that heart inside of that 5-foot-10 body is unmatched and will be sorely missed."
Barea ranks fifth in Mavericks history with 637 games played, trailing only Dirk Nowitzki and a trio of players from the 1980s (Brad Davis, Derek Harper and Rolando Blackman), whose numbers hang from the American Airlines Center rafters.
Barea played for the Minnesota Timberwolves from 2011 to 2014, returning to Dallas after he received a buyout from the final season of his contract.
"Dallas is my second home after Puerto Rico," Barea said, his voice cracking and eyes welling up with tears. "It's just special, man. It's the happiest place that I ever played basketball."
Cuban has said on several occasions that he envisions Barea having a role with the Mavericks organization after his playing career ends, which Nelson reiterated Thursday.
"In the future, I would love to come back and help this team again," Barea said. "My goal is to coach at the highest level, and I know I will be great, especially here in Dallas. I definitely want to play this year, take a break after with the family and enjoy my kids, but I want to stay around the game."
Throughout his years with the Mavs, Barea has been heavily involved in helping the community, both in Dallas and his native Puerto Rico. It was that side of Barea that Cuban, who allowed Barea to use the team plane to make several trips to Puerto Rico delivering supplies after Hurricane Maria hit the island, highlighted Thursday.
"JJ is a Mavs Legend," Cuban wrote in a message to ESPN. "What he did on the court is just a small part of who he is. Of course the title is big, but what he does for Puerto Rico, what he always does for people in need, will always be even bigger."