Last spring, the NBA was filled with playoff drama as the Nets, Cavaliers, and Sixers vied for the final two Eastern Conference playoff spots right through the final minutes of the regular season, and Chicago, Washington, and Indiana muscled about for seedings and home court advantage inside the bracket. Out west, Minnesota and Memphis dueled for the last postseason spot while Denver and Houston roared into the middle of the bracket looking like teams no one would want to face in the first round.

Don’t expect that kind of excitement this season. With less than a week to go before the All-Star Break, the playoff picture is surprisingly set – especially in the East, where the top three slots are close to being etched in stone with the names “Pistons,” “Heat,” and “Nets.” After that, Cleveland, Washington, Indiana, and Milwaukee are rapidly solidifying their places. Philadelphia and Chicago will vie to be Detroit’s speed bump en route to the conference semifinals, but that’s not much for excitement.

The best chance for April madness is in the Western Conference, where two races figure to go down to the wire. Dallas, which has gone 15-3 in 2006, and San Antonio, which has countered with a 13-2 run, will likely vie for the conference’s top seed until the final week of the season. It wouldn’t be a surprise to see both teams pass the suddenly middling Pistons (4-4 in their last eight games) for the league’s best record as they try to top each other.

But there’s more drama to be found at the bottom of the Western bracket, which is where the focus should be after Sunday’s shiny exhibition game. The sixth, seventh, and eighth seeds in the West – New Orleans/Oklahoma City, Memphis, and the L.A. Lakers as of last night’s action – all have vulnerabilities. Can any of the outsiders – Houston, Sacramento, Golden State, Utah, and Minnesota – catch them?

Memphis has the strongest case for staying in the bracket. As is the case with any Mike Fratello team, the Griz play absolutely suffocating defense, ranking third in Defensive Efficiency at 103.6 points allowed per 100 possessions. Furthermore, their +2.1 point differential argues they are a tad better than their 27-23 record would indicate. It might come via a series of 84-75 games, but the Griz seem likely to claim a playoff spot.

The Lakers also have a point differential (+1.1) that betters their actual won-loss record. But the Lakers are more vulnerable than the Griz because their lineup is more dependent on a few players. Beyond Kobe Bryant, the Lakers have four players playing just above league average – Lamar Odom, Brian Cook, Chris Mihm, and the rest of the roster can’t really be called a supporting cast because they aren’t doing any supporting. Even a minor injury to Odom, Cook, or Mihm would damage the Lakers’ ability to hover around .500. An injury to Bryant almost certainly pushes them out of the playoff picture altogether.

The New Orleans/Oklahoma City Hornets have been one of the big feel-good stories of the season, but they are definitely overachieving. (If you’re thinking they looked impressive against the Knicks on Friday night, remember how difficult it is not to.) Their 27-23 record is out of line with their -0.5 point differential. The Hornets’ dramatic improvement has been led by stellar rookie Chris Paul, but the point guard is out with bruised ribs and was playing through injuries to his thumb and sacrum. Even if he’s healthy, Paul and the Hornets figure to slip a little after the break, but if the pounding of an NBA season start to take its toll on his minutes or his production, then they will slip a lot.

So who is in position to move up? None of the current Western Conference outsiders inspire much fear.

Timberwolves fans might be better off hoping that a second straight postseason at home is enough to force owner Glen Taylor to bring in a GM who can put a team around superstar Kevin Garnett while he’s still in his prime. Minnesota’s point differential of -1 offers scant hope of an upgrade.

Although Golden State’s record is just 23-27, their point differential is even, which argues that they are actually a .500 caliber team. The Warriors have improved a little since moving Mikael Pietrus into the starting lineup, but .500 may be their ceiling. The question then becomes not whether they will make the playoffs, but whether the playoffs will stoop to include them.

Utah figures to improve if Carlos Boozer, who played his first two games of the season this weekend, suddenly regains his old form. But fans in Salt Lake City have been waiting 18 months for that to happen. If he does, the Jazz’s frontline of Mehmet Okur, Boozer, and Andrei Kirilenko could offset their backcourt weaknesses and lead a second half surge.

Sacramento and Houston are the two most intriguing teams in the playoff mix. Sacramento is just 5-4 since trading for controversial forward Ron Artest, but they have won five of seven with a much-improved defense as Artest has gradually shaken off the rust from his seven-week layoff. Further abetting the Kings’ case is their point differential of +0.1, which argues that they are better than their 23-28 record indicates. Artest’s rescue mission will make for an irresistible angle as winter turns to spring.

With their victory over the Knicks on Sunday, the Rockets, winners of six out of seven, are almost as hot as their fellow Texans. And with Yao Ming and Tracy McGrady recovered from their injuries, Houston seems poised to go on a tear. Still, the Yao and McGrady returned to a team that was 15-29. A playoff spot would probably require at least a 27-11 finish. The Rockets play just six road games between now and the start of April, so they could go on quite a run, but it’s rare for a team with no history of doing so to play .710 ball for nine weeks. It seems more likely that Houston will play spoiler rather than spoil some higher seed’s championship dreams.

mjohnson@nysun.com