Ellis, 28, a nine-year veteran, has emerged as a capable sidekick for Dirk Nowitzki, who calls Ellis the most dynamic penetrator he's ever played alongside. Ellis is shooting 45.5 percent this season, his best field goal percentage since 2007-08.
"We love him," Mavs coach Rick Carlisle said. "He's been a godsend for us. He fits what we're doing, he fits with Dirk. He's been extremely coachable. He's our leading minutes guy, so in many ways you could say he's as important as any guy we've got on this team.
"And it says a lot that he says, 'Look, it's not all about money. It's about getting to a situation that's best for me, where I can be a part of a team growing and winning.' You've got to respect those things."
Ellis said he wishes Golden State well and appreciates the warm welcome Warriors fans give him when he returns, but he said he no longer feels any extra emotion when he plays his former team.
"Those days are behind me," Ellis said. "I'm feeling good. I'm glad I'm in a happy place."