Guard Chris Duhon is a better player than a quick glance at his numbers suggests, but it is the “how” more than the “who” that makes him an important addition to the Knicks.

We’re in an odd time in the NBA offseason — word about all signings is unofficial until the July 9 announcement of the salary cap and luxury tax ceilings — but Duhon’s agent Kevin Bradford has told many press outlets that his client has agreed to a two-year deal for the full mid-level exception (about $5.8 million a season; the exact number will be part of the salary cap announcement on Wednesday). The Knicks outbid the Orlando Magic, who were offering a three-year package thought to be worth $12 million.

There may seem to have been an awful lot of fuss over Duhon, a player who last season was a reserve for a losing team, the 33-49 Chicago Bulls, and, even worse, fell out of the rotation after the acquisition of Larry Hughes, an overpaid, mediocre guard. But Duhon brings a lot of value that the Knicks sorely need in their backcourt.

Despite standing only 6 feet, 1 inch, Duhon is a good defender. In Chicago, the Bulls often used a three-guard alignment with Duhon, Ben Gordon, and Kirk Hinrich, and Duhon frequently guarded the tallest wing player and did well despite height disadvantages. Duhon understands that defense starts with the positioning of the feet, not the hands, a concept whose realization has been sorely lacking on the Knicks in recent years.

Duhon is also a pass-first point guard in the very best sense of the word. He looks to set his teammates up well before he looks for his own shot. A good example of this is to look at Duhon’s production on a per-36-minute basis. This enables us to see what his numbers would be like as a starter. During his four seasons in Chicago, Duhon averaged 6.3 assists and only 1.9 turnovers per 36 minutes; the starter, Hinrich, another pass-first point guard, notched an almost identical 6.5 assists and 1.9 turnovers.

At Madison Square Garden last season, meanwhile, Jamal Crawford ran the point most of the season and averaged 4.5 assists and 2.2 turnovers. Duhon represents a clear upgrade at point guard over the incumbent; his arrival will enable Crawford to move back to his natural position, shooting guard.

Another asset that Duhon brings to the team is his experience with up-tempo ball. During the last four seasons, Duhon has played on teams that ran the 11th-, fifth-, sixth-, and 11th-fastest tempos in the NBA. The Knicks have not run at better than the 15th-fastest tempo in the last four years. New coach Mike D’Antoni’s system is likely to be an up-tempo game, as his Phoenix teams were in the top four in possessions per contest in each of the last four seasons. So the new point guard is a good fit for the coach’s desired style of play.

Despite the on-court assets that Duhon brings to the Knicks, the biggest and most important aspect, once again, is the “how,” or, put simply, the length of his contract. By filling a void without extending the Knicks’ stay in salary cap purgatory, the new team president, Donnie Walsh, is walking the walk. He has spoken repeatedly of achieving cap flexibility by 2010, the summer that superstars such as LeBron James, Dwyane Wade, and Chris Bosh can become unrestricted free agents. (While the focus has been on James, I suspect Bosh is the most likely of the three to wind up at the Garden. James has close ties to Nets part-owner Jay-Z, and that team hopes to start playing in Brooklyn in 2010. Wade may find himself on a good team in Miami, which would diminish his desire to leave. Bosh is probably the best NBA player who is not well-known in the mainstream.)

The Duhon signing also most likely spells the end of Stephon Marbury’s tenure as a Knick. The embattled point guard has said all the right things since D’Antoni’s hiring two months ago, but Marbury is the very definition of a shoot-first point guard, which is not what the new coach wants quarterbacking his team. When D’Antoni took over in Phoenix a quarter of the way though the 2003-04 season, he inherited a team directed by Marbury. The guard was sent packing a mere 13 games later for draft picks and role players with expiring contracts. I think the Knicks have held on to Marbury so far this offseason to see if any deals could be swung, as Marbury’s $22 million contract expires after this season. But the locals need cap relief more than any other team, so buying him out and reducing the payroll for next season seems the most prudent approach.

That Marbury is on the way out has been one of the worst-kept secrets in the New York sports world this summer, but Duhon’s arrival hastens the departure. It’s not the promise to Duhon of a chance to start — anyone arriving onto a bunch of misfits like the Knicks should receive a shot at cracking the starting five — but the length of the new guard’s contract that guarantees Marbury’s departure. By using the entire mid-level exception to sign a player for two years, Walsh has shown that he’s made a plan and is sticking to it.

mjohnson@nysun.com