It should come as no surprise that the San Antonio Spurs and the Dallas Mavericks are about to embark on another duel for the Southwest Division title. In three of the last four seasons, the two have finished either tied or separated by one game. And in each of those seasons, the Spurs edged their rivals to the north; twice, it was San Antonio’s first step toward the NBA championship. The matchup has become one of the great rivalries in pro hoops, and it resumes Thursday night in San Antonio.

Most pundits are projecting San Antonio to win this year’s battle. In terms of team personalities, the Spurs are always among the top defensive teams in the league, whereas the Mavericks are known for their relentless offense. The enduring stereotype maintains that the better defensive team comes out on top. But this year’s race deserves closer examination. The remaining schedule favors the Spurs, but several other factors suggest the Mavericks are the better team and should finish ahead of their rivals.

Entering last night’s games, the Mavs lead the Spurs by one game, 44-11 to 43-12, and a snarky San Antonio fan might say the difference can be summed up in a single word – Pistons. There’s some truth to that. The Spurs have lost to Detroit twice this season, while the Mavericks handed the Pistons their worst loss of the season, a 119-82 blowout in Dallas on November 19. Of course, the Mavericks will be hard pressed to leave the Palace of Auburn Hills with a victory on March 28.

The two Texas powers also have two head-to-head games remaining, both in San Antonio. The Mavs have compiled a solid 19-7 record on the road thus far, and they will need to maintain that; Their road slate still includes games against such playoff-bound teams as Cleveland, Phoenix, the L.A. Clippers, and the Nets. San Antonio’s toughest road games are two against the Clippers and one visit to Phoenix.

The remaining road schedules would tip the balance if the Mavs and Spurs were as closely matched as their records imply. When you delve deeper into their records, however, they appear to be strikingly different teams.

The Mavericks point differential of 7.1 points per game indicates they are playing just slightly over their heads right now. According the to stats page at www.knickerblogger.net, Dallas’s margin of victory is consistent with a 39-16 team. However, the Spurs, a team that usually fares much worse than their point differential indicates (i.e, they are usually a better team than their record implies), are on the wrong side of that ledger this season. Their 6.7 point differential is consistent with a 33-22 team, a far cry from the 43-12 record they sported going into last night’s game against the Knicks.

The difference is particularly surprising given the teams’ respective offseasons. The Spurs moved aggressively this summer to add former Mavs Michael Finley and Nick Van Exel to the backcourt. They also signed top European big man Fabricio Oberto.

Aside from bidding a very public goodbye to Finley – Mavs owner Mark Cuban blogged about how the swingman’s departure marked a shift in how teams should budget – the Mavericks’ main off-season move was signing former draft bust Desagana Diop to a two-year deal. Back at the start of the season, no one would have ventured that the Mavericks had the more productive offseason, but they have. Although Diop is still very much a work in progress (he’s shooting 43.9% from the field and 53.7% from the line), he has solidified the Dallas defense, blocking a shot every 10 minutes of play.

San Antonio’s off-season acquisitions have been busts so far. Finley is having his worst year as a pro. The veteran swingman is shooting an atrocious 38.1% from the field, 6.7% below his career average, and is barely getting to the foul line, averaging fewer than two attempts per game. After averaging 35.8 minutes per game in 10 seasons with the Mavs, Finley is seeing just 26.7 minutes a game this season and is clearly struggling to adapt to his supporting role. He also turns 33 next week, and time may have caught up with him.

There’s no question that Van Exel has also been a disappointment, averaging only 5.3 point per game in barely 15 minutes a night. Oberto, averaging 2.1 points and 2.3 boards in 8.9 minutes a game, is experiencing the year of acclimation that most European players seem to need before bringing their games up to speed.

So instead of being bolstered by newcomers to the roster, the Spurs are more dependent than ever on their big three – power forward Tim Duncan, swingman Manu Ginobili, and point guard Tony Parker. Their most reliable support comes from ace defender Bruce Bowen and reserves Beno Udrih and Nazr Mohammed.

By contrast, Dallas has developed a deep and dangerous team. MVP candidate Dirk Nowitzki is the undisputed leader, but fellow All-Star Jason Terry can carry a lot of the load, too. The team also features rising stars in swingmen Josh Howard and Marquis Daniels, as well as second-year point guard Devin Harris. The bench includes solid veteran role players like Keith Van Horn, Jerry Stackhouse, and Erick Dampier, each of whom could start for a lesser team.

This Mavs’ depth and the Spurs’ lack of it should enable Dallas to endure its schedule disadvantage and win the Southwest Division, forcing the defending champions onto a tougher road for their title defense.