The Dallas Mavericks have won 12 of their last 13 games, and for the second straight season, they are in the top 10 in fewest points allowed, a stark change from a few years ago when the Mavs seemed determined to simply outscore all comers. The turnabout occurred after the Mavs changed coaches, from Don Nelson to former San Antonio assistant, Avery Johnson, and it has led more than a few commentators to credit Johnson with completely revamping the Mavs’ personality.

And he has, but the change isn’t the obvious one.

The Mavericks team that plays the Nets in the Meadowlands tonight isn’t the top defensive team that their points allowed a game average suggest, but they are still a radically different team than they were two years ago. The change is in pace. Unlike the fun ‘n’ gun Mavs of Don Nelson, who coached the team from 1998 until late in the 2005 season, the current Mavericks play a very slow tempo.

With an average of 92.3 possessions a game, Dallas currently ranks 26th in pace, or put another way, only four teams milk the 24-second clock more than the Mavericks. Last season, they ranked 27th, with 87.8 possessions a contest. To give local fans a point of reference, the last Knick team to advance past the first round of the playoffs, Jeff Van Gundy’s 2000 squad, played almost that deliberately, averaging 89.2 possessions a game. During their peak season, Nelson’s Mavs averaged nearly 95 possessions a game.

The change of pace has affected the Mavericks’ stats on both sides of the ball. On offense, the Mavericks are averaging 99.5 points a game, a far cry from the tally of league leader Denver, 109.1, and a good bit shy of the Nelson team from three seasons ago that was quarterbacked by point guard Steve Nash and averaged 103 ppg. That team led the league in Offensive Efficiency, scoring 110.9 points per 100 possessions, and the current Mavs are right near the top too, ranking third at 107.3. Yet the two teams couldn’t be more different.

The 2003 Mavs raced up court, and the first player with an open look took a jump shot or attacked the rim. That team resembles Nash’s current squad, the Phoenix Suns, more than they do this year’s Mavs. Now, a typical Dallas possession involves a methodical series of passes through the post and around the perimeter. With the shot clock running down and the defense scrambling back from double teams, the Mavericks — particularly, forwards Dirk Nowitzki and Josh Howard, and guard Jason Terry— catch, dribble to a spot, and either shoot or find a teammate with a better prospect.

This change in offensive philosophy accounts for some of the change in Dallas’ defensive numbers. With substantially fewer possessions per game, there are fewer chances for opponents to score, and that accounts for some of the change in Dallas’s defensive numbers. However, Johnson has improved the Maverick defense. During the Nelson era, the Mavericks only got out of the bottom quarter of the league in Defensive Efficiency twice, and once was with Johnson in the fold as a player/assistant coach. With Johnson in full command, the Mavericks finished 10th last season and rank 15th so far this season.

In other words, Johnson hasn’t made the Mavericks into a defensive power. Instead he’s taken a top uptempo team and made them into a top halfcourt team. In addition, he’s taken a bad defense and made them respectable. These are no small feats.

What’s more is that Dallas maintains the capacity to push the tempo when necessary. Against San Antonio two weeks ago at the AT&T Center, the Mavericks won by racing out to a big lead before San Antonio could settle into a groove. In fact, the Mavs’ biggest failing tends to be trying to beat teams with their methodical approach, when they should put the pedal to the metal. Last summer’s NBA Finals were the best example of that tendency.

As we noted last week in discussing Detroit, pace frequently distorts offensive and defensive production, and perhaps this year more than ever. During the off-season many GMs spoke about wanting to get more athletic and play an uptempo style. And it is true that pace across the league is up, but those teams that are running more are burning more calories without actually seeing results. Dallas and Detroit aren’t the only slowpokes crowding the leaderboard in Offensive Efficiency. Utah, Seattle, San Antonio, and Cleveland are all in the bottom half of the league in pace but in the top 10 in Offensive Efficiency. Phoenix, the team that many GMs want to emulate is in the top three in both categories, but its copycats have a long way to go. When it comes to NBA offense, faster just means faster, not necessarily better.

mjohnson@nysun.com