It’s reasonable to assume that Knicks President Isiah Thomas and his Nets counterpart, Rod Thorn, are watching the NBA Finals, but local fans should hope they are taking copious notes, too. The finalists, San Antonio and Detroit, didn’t get there by accident, and each has a good shot at remaining among the NBA elite for years to come. Both franchises followed three key tenets that the local hoops bosses should learn from as the Knicks rebuild and the Nets fine-tune their team.

1 Size Matters. Center and power forward are two of the three most important positions on the floor. It is virtually impossible to make the finals without an All-Star-caliber performer in the paint. Even the Chicago Bulls, who built their dynasty around Michael Jordan and Scotty Pippen, relied on stellar inside play from Horace Grant and Dennis Rodman during their championship runs.

San Antonio’s drafting of Tim Duncan in 1997 was a no-brainer, but their midseason acquisition of Nazr Mohammed from the Knicks was inspired. Even more impressive was Detroit GM Joe Dumars’s deal for Ben Wallace following the 1999 season. The two-time Defensive Player of the Year was considered a one-dimensional player at the time, and was a throw-in in the sign-and-trade deal that sent Grant Hill to Orlando. Similarly, where other teams saw a head case in Rasheed Wallace, Dumars saw a big, athletic body that helped transform last year’s Pistons into one of the best defenses the league has ever seen.

By contrast, the Knicks have finished two of the last three seasons with a center-by-committee consisting of power forwards. Kurt Thomas and Michael Sweetney have been forced to play out of position, spending all their defensive energy just to wind up in foul trouble while guarding bigger, stronger foes.

The Nets are almost as bad. Jason Collins makes a fine reserve center, but he’s been an inadequate starter for four seasons; at times this season, Nenad Krstic, a fine rookie power forward, was forced to play the pivot. Making matters worse, the Nets did little to fortify the middle after shipping out big men Alonzo Mourning, Aaron Williams, and Eric Williams in the Vince Carter deal.

The failed experiments with Mourning and Dikembe Mutombo should be more than a cautionary tale. Both the Nets and the Knicks need to resolve the malaise in the middle by making the pivot their first off-season personnel move. The draft is flooded with 7-footers, and a smart pick could be a crucial step away from mediocrity.

2 Frugality pays. The finals are pitting the 19th-highest payroll in the league (Detroit) against the 24th (San Antonio). Talk about bang for your buck. That’s not a fluke: The Western Conference finalist, Phoenix, ranks 25th, while the Eastern runnerup, Miami, ranks 12th. On the other end of the spectrum, eight of the league’s 10 most spendthrift teams were done for the year by the end of the first round.

The Pistons and Spurs have been so frugal that next year, when big, new contracts for Detroit’s Tayshaun Prince and San Antonio’s Tony Parker will go on the books, both teams will still be substantially under the luxury-tax threshold, which is likely to be around $62 million. Examine both rosters and you won’t find any of the what-were-they-thinking type contracts that typify many obese NBA rosters – most notably the Knicks’.

Instead, smart clubs like the Pistons and Spurs sign their players to money that is in line with or even below what their performance warrants. Their core players seem to accept that policy in the interest of making room for better teammates; Parker and Rasheed Wallace have both accepted less money than they could earn elsewhere, presumably because they like winning. Duncan, one of the NBA’s top five players, is only its 20th highest-paid.

By contrast, the Knicks are so far over the salary cap that they won’t be able to import enough young talent to be a contender for at least the next two seasons. New York is still on the hook for Allan Houston (two more years at a total of nearly $40 million),Tim Thomas and Anfernee Hardaway (one each at $14 and $15 million respectively), and Shandon Anderson (two more years at $14 million, which was already bought out but remains a cap obstacle).

If he is to attract top players, Isiah will have to promise future free agents that the prospect of winning in New York will boost their endorsement profile high enough to make up for possible shortfalls in their annual salaries. He may also do to look across the river, where the Nets seemed to have learned their lesson in the wake of the Mourning ordeal. Indeed, the Nets signed Richard Jefferson to a $76 million deal that, while sizeable, was below the maximum.

3 Roster-filler counts. Talent evaluation is the first phase in building a championship team. That lesson is being vividly illustrated in the Finals, where journeymen, late first-round draft picks, and unheralded foreign players are all playing key roles. Pistons point guard Chauncey Billups has spent time on four other teams; Spurs ace defender Bruce Bowen has played on three. Parker was drafted with the 28th pick of the 2001 draft, Prince was the 23rd pick the following year, and Manu Ginobili, a relative unknown player in Italy, was chosen with the 57th overall pick in 1999.

The Nets, meanwhile, have filled out their roster with the likes of Ron Mercer, Jabbari Smith, and Billy Thomas, and gave away their first-round pick last year in a cost-cutting move. The Knicks have done even worse; they’ve consistently brought in aging, overpaid players, and in Isiah’s second move on the job, they dispatched two high-upside foreigners – Milos Vujanic and Maciej Lampe – to Phoenix as throw-ins in the Stephon Marbury deal.

With the off-season just a week away, both the Knicks and Nets must recognize quickly where they have failed in recent years and set about correcting those errors. Neither club can afford not to. Without a better center and a deeper bench, the Nets will find it nearly impossible to advance past the second round. Without shrewd personnel judgment in all phases of their talent acquisitions – drafting, signing free agents and scouting European players – the Knicks will continue to flounder. Let’s hope that Thorn and Thomas are watching these Finals very closely.