Jeff Zillgitt

USA TODAY Sports

MIAMI — Boris Diaw backed down Dwyane Wade, and Chris Bosh came to double-team.

Diaw slipped a deft behind back pass to Bosh's man, Tiago Splitter, who finished with an easy one-handed dunk.

"Every time," Diaw said to Splitter as the San Antonio Spurs got back on defense.

It wasn't quite every time, but Diaw had his hands in enough plays to impact the outcome for the second consecutive game. The 32-year-old almost had a triple-double with eight points, nine rebounds and nine assists in San Antonio's 107-86 Game 4 victory at the Miami Heat, helping the Spurs to a 3-1 lead in the NBA Finals.

"You know, Boris pretty much does the same thing every night as far as helping us be a smarter team, at both ends of the floor," Spurs coach Gregg Popovich said. "He knows what's going on most all the time. At the offensive end he's a passer. He understands mismatches. He knows time and score. At the defensive end, he knows when to help. He's active.

"So he just helps the whole team have a better IQ."

Diaw has turned into one the unlikely stars in the NBA Finals.

Two seasons ago, Diaw had been marginalized and wasn't part of the Charlotte Bobcats' future under coach Paul Silas. He played in just four games in the first three weeks of March 2012, and Charlotte waived him.

The Spurs picked him and turned him into a contributor. Of course they did.

Popovich inserted Diaw into the starting lineup for Game 3, following San Antonio's Game 2 loss.

"Boris is a good all‑around basketball player, so he can do several things at both ends of the court," Popovich explained. "And we thought that we probably would need that just to have the best opportunity to play good basketball. He allows us to have more variety in our offense, and he's an underrated defender."

Diaw doesn't look like a basketball player, more doughy and portly than muscular, but Popovich is correct. Diaw is smart and knows how to play. He's a point-forward, able to run the offense from any spot on the floor.

"Implementing Diaw into the lineup has given them another point guard on the floor," Heat star LeBron James said. "So Manu (Ginobili), Tony (Parker) and Diaw and Patty Mills on the floor at once, they've got four point guards basically on the floor at once. So all of them are live and they all can make plays. So it's a challenge for us all."

The Spurs' efficiency with Diaw on the court vs. the Heat is amazing through four games. He has the second highest-efficiency rating (behind Manu Ginobili) of any Spurs player with regular minutes. The Spurs are scoring 125.0 and allowing 91.9 points per 100 possessions when Diaw is in the game.

He is nearly the perfect prototype for the Spurs' system: willing to play defense and share the ball without worried about scoring.

Beyond his nine assists, he also had three secondary "hockey' assists. That's the pass that leads to the pass that leads to the basket.

"I always try to read on the floor who is going to be open," Diaw said. "We all try to make good passes. Everybody on our team is reading, including me, but we don't want to go for the home run pass. We try to make the right pass, and sometimes the easy pass is the right pass."

The Spurs had 25 assists on 40 baskets and 15 secondary assists compared to 13 assists on 32 baskets and three secondary assists for Miami.

"They move the ball extremely well," James said. "They put you in so many difficult positions. If you're not right on time, right on target, they're going to make you pay for it. ... They can shoot the ball from outside, they can also penetrate. So our defense is geared towards running guys off the three‑point line, but at the same time those guys are getting full steam ahead and getting to the rim, too."

Diaw has performed well in the playoffs, not only the Finals, averaging 9.4 points, 4.6 rebounds and 3.3 assists in 22 postseason games. He had 26 points in Game 6 and 14 points and 10 rebounds in Game 2 against Oklahoma City in the Western Conference finals. He had 17 points and key three-pointer in Game 4 against the Dallas Mavericks in the first round.

Parker, the Spurs' starting point guard, has known Diaw for years, and they have played together on the French national team. Last summer, they led France to its first Eurobasket championship, beating Spain the semifinals and Lithuania for the title.

"I'm just very happy for him. Very proud of him. He's playing great basketball," Parker said. "I've known him for so long. It's almost like a dream right now just playing with him for the NBA Championship. Just watching him out there and just showing everybody what he can do.

"I've been seeing that every summer because I played with him in the national team, and he's always been a great player with us."

Parker said Charlotte wasn't the right situation for his friend.

"He's the ultimate team player and needs a system," Parker said. "He's a perfect fit for us."

Jeff Zillgitt is an NBA insider for USA TODAY Sports. Follow him on Twitter at @JeffZillgitt.