If Celtics  coach Doc Rivers  is really “the Bill Belichick  of basketball,” as Jason Terry  claimed , then he’s planning to stop every opponent’s most dangerous weapon. Against the Mavericks on Wednesday night, that’s O.J. Mayo.
The fifth-year guard has averaged career highs across the board, including 20.8 points (48.7 FG%, 50.3 3P%), 4.0 rebounds and 3.5 assists in 34.9 minutes per game, leading Dirk Nowitzki -less Dallas to a surprising 11-10 start.
“O.J. Mayo’s playing off the charts,” said Rivers. “He’s shooting above 50 from the 3. What’s impressive with him, they’re running a lot of isos, and he’s guarded taking 3’s. That’s scary when you say a guy is guarded taking 3’s and he’s making over 50 percent of them. And he’s really their catalyst.”
After the NCAA  vacated his brief USC career over improper benefits, Mayo played his first four NBA seasons for the Grizzlies . That roller-coaster ride began with a runner-up finish to Derrick Rose  in the 2008-09 Rookie of the Year voting and ended with a sprinkling of votes for last season’s Sixth Man of the Year honor, but also featured an in-flight fight with Tony Allen  over a gambling debt and a 10-game suspension for using a banned substance.
“His work ethic has definitely changed,” said Celtics guard Jason Terry. “If you hear coming out of their locker room what he’s done differently, he’s brought better work habits. He’s been there at night, and he’s coming early before the games, so I think that’s carrying over for him. He’s always been a great talent, but there’s been questions about his work ethic. Obviously, this year he’s put the work in, and it’s starting to show.”
The signing of Mayo to an affordable one-year, $4.0 million deal (with a $4.2 million player option for 2013-14 that he probably won’t pick up) has helped ease the shooting guard transition from Terry in Dallas. Oddly, if C’s had succeeded in any of their many attempts to acquire Mayo over the last several years, including a Ray Allen  trade that collapsed last season, the two might be wearing different jerseys in the Garden on Wednesday night.
“I’m sure it does [motivate Terry], and it probably will for O.J., because he’s the new guy for them,” said Rivers. “That’s just human nature. What you don’t want to make it is bigger-than-life competition. … I’m sure JT will have some stuff. He loved it there, but now it’s his old team, and you know how that goes.”
Rather than focusing on what might have been, Terry must focus on what is, and that’s Mayo’s torrid shooting from everywhere on the floor. As Rivers said, he’s shooting 50.0 percent (23-46 FG) on isolation plays, but he’s also having success spotting up (41-72 FG), in transition (39-71 FG) and as the pick-and-roll ball handler (25-57 FG).
“You can see our ball pressure getting better,” said Rivers. “Our traps are so much better than they were earlier in the year, and the rotations are the whole key to the traps. The biggest part is not as much dribble penetration. When you don’t have dribble penetration, you have better rebounding, and we’re starting to rebound better.”
Overall, the Celtics have actually ranked among the NBA’s top five defensive teams against isolation plays, pick-and-roll ball-handlers and spot-up shooters. So, really it’s Mayo’s transition scoring, his 3-point shooting and any roll man that benefits from the defensive focus on him that the Celtics have to worry about. The C’s rank dead last, 12th and 26th in those three defensive categories, respectively, although that’s improved in their last five games.
“Our bigs are doing a better job of being aggressive,” said Celtics point guard Rajon Rondo , who might check Mayo now that the Mavs start 38-year-old Derek Fisher. “That’s helping our guards a lot. That’s helping me a lot — with them blitzing the pick-and-roll and making the guards pick up the ball and making their bigs make plays.”
So, while the C’s attempt to hold the Mayo, they’ll force other Mavericks to beat them. Just like Belichick.
“[Chris] Kaman ‘s playing well,” said Rivers. “Vince Carter  has clearly went to the Hot Tub Time Machine. I mean, he’s playing terrific. He’s dunking. He’s jumping. So, Rick [Carlisle]’s doing a heckuva job with that team. Having Dirk out and playing the way they play is pretty impressive.”