When you lose your job in professional sports, much like DeJuan Blair did last summer, you’ll play just about anywhere to keep your dream alive. It just so happened that his new employer has put him in the enviable position of driving his previous employer nuts.

Blair wants to beat the San Antonio Spurs in this Western Conference quarterfinal series. His motivation is simple. He told reporters at the start of this season that he didn’t feel the Spurs “believed in him anymore.” He gave the Spurs tough minutes off the bench for four years, backing up Tim Duncan. But after four seasons, the Spurs didn’t ask him to return.

Spurs head coach Gregg Popovich doesn’t need reminding. But, just in case, in game 6 Blair did his best impression of the high school underachiever who came back to the reunion and impressed all his old classmates. Blair’s 10 points, 14 rebounds and 29 minutes off the bench — including playing the entire fourth quarter — changed the whole complexion of the Mavs’ 113-111 win and, perhaps, Blair’s long-term future in Dallas.

“His energy was great,” Popovich said. “He was all over the floor. He was like a man possessed at both ends of the floor. He was physical, and he played good basketball on top of that. I thought he was super.”

The fact that Blair felt dissed by the Spurs last summer was compounded by his suspension for game 5 of the series. Blair had to watch that game from his hotel room in San Antonio after he was suspended for kicking former teammate Tiago Splitter in the head. After he was ejected, it seemed to suck the life right out of the Mavericks.

Dirk Nowitzki said Blair genuinely felt bad about having to miss game 5. While not referencing the suspension, head coach Rick Carlisle noted that Blair gave the Mavs a “real physical presence” and that he “clears out a lot of space.”

Of course Blair’s style of play isn’t a real surprise. The Spurs know Blair is physical, and the Spurs know he’s emotional. It’s just that the tables are now turned. It’s one thing when a player like Blair is on your side. It’s quite another when he’s on the other side.

“They [the Spurs] know what I can do,” Blair said. “They know how I play. I did it for that team, and now I’m doing it for this team. I have to bring all of that energy and all of that emotion here.”

Perhaps the Spurs were unable to find Blair a proper role in their rotation because they had other players who shared his traits. The Mavericks don’t. He’s the Mavericks’ toughest interior player since Tyson Chandler manned the paint during the Mavs’ 2011 championship run. Chandler funneled his toughness through his height (he’s 7-foot-1) and his intimidating wingspan.

Blair has more in common with Charles Barkley, the Hall of Famer dubbed the “round mound of rebound.” Blair gives up six inches to Chandler, but he weighs in at 265 pounds. He creates room with his girth and with his force of will. Like a great scorer, Blair feeds off what he does best — rebounding, playing defense and setting powerful picks.

Although Blair’s regular-season per-game averages were rather pedestrian — 6.4 points and 4.7 rebounds — this playoff run is exposing his true value to the Mavs and to the rest of the league. The Mavs have stumbled across a player who brings them something they’ve craved since they let Chandler go, which was the franchise’s biggest recent mistake.

The Mavs only signed Blair through this season. He seems comfortable in Dallas. It sounds like he enjoys his role with this team and appreciates the support he says he’s getting from Carlisle, Mark Cuban and the rest of his new teammates.

The best part for the Mavs is that Blair is just 25, so they would be getting a player with plenty of good years ahead of him. There should be little doubt in the Mavericks’ mind that keeping Blair in Dallas is a priority.

But the contract can wait a few more days. Blair has another priority. “Winning game 7 on [San Antonio’s] court would be the best revenge,” he said.