Dallas signed Mayo, the third overall pick in the 2008 draft, to a one-year, $4 million deal with a player option for a second season after he spent four often frustrating seasons with the Memphis Grizzlies.
Mayo's best statistical season was his rookie year, when he averaged 18.5 points, 3.8 rebounds and 3.2 assists. He posted similar but slightly lower numbers the next season, and his statistics declined significantly while serving as the Grizzlies' sixth man the last two years.
Mayo was one of several acquisitions the Mavs made after after their attempt to lure Deron Williams to Dallas was unsuccessful.
"We went on the option for the big free agent. That didn't work out. Honestly, that wasn't my first choice," owner Mark Cuban said Monday. "Sometimes the best deals are the ones you don't do and they lead to better things. And I think that's what happened now."
Dallas also got Elton Brand on a waiver claim from Philadelphia, signed free agent Chris Kaman, and acquired Darren Collison and Dahntay Jones in a trade from Indiana. All those moves were made in July.
The Mavs hope Mayo, who is expected to start at shooting guard in Dallas' revamped lineup, will end up being the best bargain of this summer's free agency class.
"I think he can be a star," said Cuban, who insists he sees a long-term future for Mayo in Dallas. "And I think O.J. knows that this is his make-or-break, who-am-I-really-going-to-be-in-this-league year. Coach (Rick Carlisle) is going to give him that opportunity. We'll see what happens."
The Mavs are counting on Mayo, who averaged 12.6 points in 26.8 minutes per game for Memphis last season, to fill departed free agent Jason Terry's role as Dirk Nowitzki's scoring sidekick while playing an all-around game.
"Definitely, we want to keep Dirk's window open as long as possible to win another championship," Brand said. "We're hungry because we don't have championships and he does. Hopefully, we make his job a lot easier."
Philadelphia used its one-time amnesty provision in the new CBA to let Brand go, and the Mavs won the waiver claim. The 33-year-old two-time All-Star will make $18.1 million in the final season of a five-year contract that will be paid mostly by the 76ers.
"I've still got a lot left in the tank," Brand said. "I feel great."
Mayo thinks he has improved since his rookie year. He's eager for the opportunity to prove it.
"Being an elite player in this league and being able to bring it night in and night out is a big step for me," Mayo said. "That's what I want to prove this year. Being a starter guard in this league and player for a great team like the Dallas Mavericks, I can be an elite player night in and night out."
Added Carlisle: "His best basketball is ahead of him."
Mayo said one of the reasons he chose Dallas over teams that were offering more money -- albeit not the lucrative, long-term deal he hoped to get -- was because of Carlisle's reputation for developing young players. Mayo specifically cited the impact Carlisle made on Chauncey Billups' career in Detroit, which Billups emphasized while encouraging Mayo to play for Carlisle.
Mayo arrived in Dallas a month ago to begin daily workouts with Carlisle, saying he "gave my whole game" to the coach to refine.
"Put it this way: He's working his butt off, he's got the talent and he's got the opportunity," Cuban said. "Nobody's going to be pushing harder for him to succeed than us."
Information from The Associated Press was used in this report.