DALLAS – After O.J. Mayo put up 20 efficient points in his Mavericks home debut, coach Rick Carlisle prefaced praise of the shooting guard’s offensive performance by pointing out that Mayo made some defensive mistakes.

A couple of nights later, before Dallas’ next preseason game, Carlisle again made sure to mention that Mayo must be a good defender for the Mavs to have the kind of success they want.

It’s the same type of treatment Carlisle used to give Jason Terry, whose shoes Mayo is trying to fill as Dirk Nowitzki’s scoring sidekick.

Maybe Mayo is getting the message, but that hasn’t been evident on the floor this week. Shooting guard Kevin Martin led the Rockets with 23 points on 8-of-15 shooting in 25 minutes Monday night. Shooting guard Jared Dudley led the Suns with 16 points on 7-of-9 shooting in 16 minutes Wednesday night.

“I’ve got to get better,” Mayo said. “You can point fingers at any individual, but if you notice any good teams that get after it defensively, it’s five guys all pulling on a string. I rate myself as good as my team is.”

There’s a lot of truth to that, but here’s the trouble: The Grizzlies were significantly worse defensively with Mayo on the floor in each of his four seasons in Memphis.

According to 82games.com, the Grizzlies allowed at least 3.2 points per 100 possessions more with Mayo on the floor in each season. The difference was an eye-popping 9.1 points during Mayo’s rookie season, when he averaged a career-best 18.5 points per game.

The Grizzlies demoted Mayo to sixth man the last two seasons so they could get defensive stopper Tony Allen in the starting lineup. It might have stunted Mayo’s development, but the move helped Memphis make the playoffs in back-to-back years after a four-season postseason drought.

The Mavs, on the other hand, penciled Mayo into their starting lineup the second they signed him this summer. As far as Carlisle is concerned, the Mavs’ staff can help the Mayo develop into a good defender, even though he’s a little undersized for a shooting guard at 6-foot-4.

“He’s an old-school kind of guy, and he’s shown tremendous toughness,” said Carlisle, pointing out that Mayo refused to sit out the preseason game in Barcelona despite a freak accident leaving a bloody divot in the palm of his shooting hand. “I’ve seen him make loose-ball plays. I’ve seen him go on the floor. I’ve seen him get into people’s faces and stuff like that.

“If you have those qualities, then you can be a great defender.”

That will be Mayo’s biggest challenge with the Mavs.