As the Nets entered the off-season, their fans must have experienced déjà vu all over again. As was the case last season, and several others during the Jason Kidd era, the Nets’ president, Rod Thorn, faced the task of building a supporting cast around his stellar nucleus.

The current Nets core — point guard Kidd, guard Vince Carter, small forward Richard Jefferson, and power forward Nenad Krstic — ranks as one of the best one-through-four combos in the NBA. But the bench, well that’s another matter. Waiving the current reserves and shopping for new ones has become an annual ritual in East Rutherford. Some years it was Rodney Rogers and Lucious Harris; in other seasons, it was Aaron Williams and Travis Best.But no matter who came off the bench, the result was consistent: a steep drop-off from the starters. Given that in the NBA, the reserves typically play a quarter’s worth of action per position, the lack of solid bench production can translate to several more losses a season.

However, the Nets’ recurring problem in this area is not testament to Thorn’s incompetence. Thorn has done a stellar job in building the foundation of the team, and his deft moves two years ago to first move Kenyon Martin to Denver for three first-round draft picks rather than give in to K-Mart’s exorbitant salary was ingenious. That move then was topped by trading some of the Denver draft picks and some salary dead weight to Toronto for Carter. Instead, Thorn’s struggles indicate how difficult it is to build a solid set of reserves in the NBA.

If you look at some of the deeper teams in the NBA, you see more luck than methodology. Dallas threw money at players left and right, getting single seasons from Antawn Jamison and Antoine Walker, before landing on last year’s deep set of reserves, which included Keith Van Horn’s max contract. Chicago’s deep bench is a result of six years of high draft picks. In Memphis, Jerry West used his midlevel exception resourcefully to build a deep veteran unit.

The Nets have tried to go the Memphis route the last two seasons with little success. So this off-season, they are trying to develop a youth movement. The team is counting on their three draft picks, point guard Marcus Williams, pivotman Josh Boone, and shooting guard Hassan Adams, to contribute. In addition, the team is planning to import 7-foot-2-inch Mile Ilic, their second-round pick in 2005.

Of the four, Ilic may be the slowest to contribute. The Serbian played in the European leagues this year and his stats suggest that his game is still a work in progress. On the positive side, he shot 60.3% from the field, but on the downside, he was a soft rebounder, averaging only 4.6 in 18 minutes per contest. Just as the Nets did with Krstic two years ago, they will probably have to start Ilic deep on the bench and get him burn as the situation allows.

Williams, who is seen as an eventual successor to Kidd, played particularly well in the Orlando summer league; he averaged 16.6 points and 8 assists a game while shooting 46%. If he plays at a good fraction of that pace, many GMs are going to regret letting him slip to the Nets at no. 22 on draft night. Boone is expected to provide shot blocking and rebounding starting midseason when he recovers from shoulder surgery. Adams has had a slow summer fighting through several minor injuries, but any production from a low second round pick is a plus.

As if four rookies weren’t enough players getting carded when they order a drink, the Nets are considering adding undrafted free agent Eric Williams from Wake Forest. The 6-foot-9 pivotman played exceptionally well against ACC opponents like Shelden Williams and Cedric Simmons, both of whom were drafted in the first round. Also last year’s first-round pick, swingman Antoine Wright, used the summer to rehabilitate his stock after a dismal rookie campaign; he scored 17.2 ppg and shot 47% in the Orlando summer league.

Countering the influx of young talent, the team also brought back Clifford Robinson — the center missed the final part of the Nets season ending series with Miami due to a violation of the league’s drug policy. At worst, Robinson, who turns 40 early in the regular season, will be available to give the rookies firsthand accounts of what UConn was like in the ’80s — his, Williams, and Boone’s alma mater. His game has been in steady decline for years, and it’s hard to see the argument that it will bounce back now. The Nets also fortified their pivot getting veteran center Mikki Moore, a good defender, from Seattle for a future secondround draft pick.

The youth movement is a savvy gamble by Thorn. While the Nets nucleus is strong, Kidd is 33, which is ancient in point guard years, and Carter can opt out of his contract after the ’07 season. The Nets need to put themselves in position to try to win now and have a promising future. With some wise drafting and savvy shopping among the free agents, Thorn may have accomplished just that.

mjohnson@nysun.com