If coach Rick Carlisle knows the answer to that question when the season ends, then this year has been a success -- no matter how many games the Mavs ultimately win.
Unless, of course, Mayo opts out of his deal after the season and the Mavs can't persuade him to re-sign, but that's a story for another day.
Mayo didn't play like a difference-maker Thursday.
So good in the Mavs' first 24 games, Mayo was awful against the Miami Heat. You know what that means: The Mavs were destroyed.
This team has no chance to win when Mayo isn't a dominant offensive force.
Miami 110, Dallas 95.
Mayo scored the game's first basket. He missed seven consecutive shots until scoring on a driving layup with about nine minutes left in the third quarter.
Mayo, among the NBA's most efficient scorers this season, had been averaging 20.6 points per game on just 15 shots. Only three times has he had more shots than points scored.
"He's studied the game. He's studied his game and worked on it," Carlisle said. "You love guys who have that gym-rat love of the game. He's on a mission this year to get better and help us win games."
Dwyane Wade and Miami's tenacious, physical defense made him a nonfactor. The Heat trapped him and contested every move -- with or without the ball -- frustrating Mayo.
He finished 3-of-14 from the field, including 0-of-5 on 3-point attempts.
"We're playing a random game right now because of our personnel situation," Carlisle said. "It's not like we're running a lot of plays for O.J.
"Right now, our flow game has to be geared toward ball movement and finding hot players and finding the best players. Obviously, we need to do a better job than we did tonight."
As good as Mayo has played this season, we still don't know if he's dynamic enough to be the kind of star who can consistently impose his will on a game. The best players can't be stopped.
The only question is whether they get their points easy. Or they have to work for them.
Now, we'll see how Mayo, the third player selected in the 2008 draft, fares in his return to Memphis on Friday night.
Mayo started his first two seasons in Memphis and spent the past two as a backup. The Memphis Grizzlies, one of the best teams in the Western Conference, haven't missed Mayo.
That must be hard on a dude's ego.
Perhaps being unwanted in Memphis has made Mayo a better player. What Mayo had done entering the Miami game has been impressive no matter what facet of his game you choose to examine.
But the better he plays, the higher he raises the standard for himself.
Mayo is averaging 3.7 assists and 4.0 rebounds. And get this -- he entered Thursday's game ranked third in the NBA with 68 3-pointers made.
Mayo has been doing it without much consistent offensive help from any other starter, which has put the burden on him to score. It also means he's the epicenter of every opponent's defensive game plan -- he draws the opponent's best defender most nights.
Still, he's had 14 games with at least 20 points, and the Mavs are 9-5 in those games.
Talk to enough people around the Mavs organization and they'll tell you no one works harder on his game than Mayo.
He shows up early and leaves late. He finds gyms on the road so he can get in some late-night shooting, and he's even worked a little with Dirk Nowitzki's shooting coach.
The reality is you can't win a title without multiple stars in today's NBA. The 2011 Mavs were a wonderful aberration.
On and on it goes.
Soon, we'll see how Mayo's game evolves when Dirk returns and the offense doesn't run through him.
But we can't ignore nights like this one against Miami. Every night matters when you're trying to figure out who's good enough to help Dirk make one more legitimate championship run.