This spring is shaping up to be a Laker-hater’s dream. Not only is the Purple and Gold on course to finish well behind the Clippers, but now there’s a good chance the Lakers will be bumped from the playoff picture by their bitter rivals to the north, the Sacramento Kings. The only thing better would be seeing Jack Nicholson do a face plant while arguing a call from his courtside seat.

Let’s rewind. Sacramento, 50-32 last season, was left for dead sometime around Christmas after two substantial losing streaks left it 12-17. A perennial playoff team having its breakdown season, the Kings looked listless on the court.

The Lakers, meanwhile, looked like a solid reclamation project by coach Phil Jackson. When last seen in these parts, after a January 31 thrashing of the Knicks, they were 24-20 and the only playoff question involved who their first-round opponent would be. While Kobe Bryant’s prodigious scoring got the headlines, the real story was the improved Laker defense, which ranked among the NBA’s top 10 teams in Defensive Efficiency (points allowed per 100 possessions) after placing near the bottom last season.

Since February the Lakers have been floundering, losing 10 of 17. The Kings, following the late-January acquisition of forward Ron Artest (whom the Lakers coveted), have won 10 of 14 to close within a game and a half of the Lakers, going into last night’s games.

Can Artest push Kobe out of the playoffs? It’s a very real possibility. As you would expect from a former Defensive Player of the Year, Artest has provided a big boost to Sacramento’s defense – and the decline of the Kings from contenders to also-rans was due to their defense. After several years among the league’s top 10 in Defensive Efficiency, the Kings slipped to 21st in 2004; 22nd last year; and 25th at the time of the Artest trade.

The main reason for the defensive decline was that Doug Christie, their ace perimeter defender got old and lost his mobility. Sacramento is not a formidable team inside, so without a stopper to slow the opponent’s best perimeter threat, the Kings were reduced to ceremonial royalty. Artest restores that element to the Sacramento defense: In just six weeks, the Kings have risen from the dregs to the middle of the pack in Defensive Efficiency.

Despite the unusually fast pace of their games, Sacramento has held seven opponents under 90 points during Artest’s 14 games with the team. The Kings’ 109-84 win Monday night over the Nets was typical; they held the Nets in check and in particular, Artest harassed Vince Carter into an 8-for-22 shooting night. While the Kings offense isn’t quite as potent as it was three or four years ago, it is beginning to improve, and it’s worth noting that Artest has matched the man he replaced, Peja Stojakovic, point for point.

The Lakers’ tumble, meanwhile, has occurred on the defensive end. Oddly for such a one-man show, the Los Angeles offense has improved over the course of the season, and the Lakers currently rank in the top 10 in Offensive Efficiency. In Defensive Efficiency, however, they have slipped from seventh to 17th, one spot behind the rising Kings.

The Lakers’ failings are more diffuse than the Kings gains. Jackson’s team has suffered moderate declines across the board in offensive rebounds allowed, turnovers created, and opponents’ field-goal percentage. They are also allowing opponents to get to the rim more often, and allowing more free throws. This suggests the team has hit a wall. Indeed, it seemed for much of the first half of the season as if they were playing over the heads; many Lakers, most notably guard Smush Parker and forwards Brian Cook and Chris Mihm, were putting up numbers well above their career averages. The clock may have struck midnight on the Laker Cinderella.

Going forward, both teams have similar schedules. The teams play each other twice. The Lakers still have two tilts each with San Antonio and Phoenix; the Kings get Dallas and Phoenix twice. Last night’s game against Milwaukee completes Sacramento’s road slate against Eastern Conference teams, and the Lakers don’t have any exhausting road trips either. Thus, it will probably come down to the head-to-head matchups, and the first one is Tuesday night in Sacramento.

Fans have yearned for a Kings-Lakers rematch ever since the 2002 Western Conference Finals, in which the Lakers won an epic seven-game series that included a Game 7 overtime, Robert Horry’s game-winning shot in Game 4, and some of the worst officiating of all time in Game 6. This isn’t it. Both teams are recovering from tumbles into mediocrity, and only a handful of players remain from that series; just as important, either the Mavericks or the Spurs figure to wipe out whichever Californian opponent they face in the first round. But the rivalry is still intense, and this race may add a new chapter to the northern California/southern California feuds.

mjohnson@nysun.com