During his stewardship of the Nets franchise, we’ve been able to develop a very clear picture of Rod Thorn’s capabilities. The team president has proven to be great with the broad strokes that define the direction of the franchise, but repeatedly stumbles when it comes to the secondary moves needed to fill out a championship-caliber roster.

The events of the past three weeks give us more evidence about Thorn’s one great strength and his one huge weakness. True to his reputation, Thorn aced the two big-picture moves that will keep the franchise in reasonably good condition for the next couple years. First and foremost, he re-signed star guard Vince Carter. And second, he’s working to sign coach Lawrence Frank to a two-year extension, a move that will keep one the league’s brightest young coaches in the Swamp.

The core Thorn has built is unassailable — Carter and Jason Kidd, both acquired in masterful, one-sided trades by Thorn, are a potent nucleus. Another trade acquisition, Richard Jefferson, bolsters that trio with another star-caliber player when healthy.

Around that core, however, the Nets have struggled to build a competent supporting cast, and Thorn’s foibles have been a major reason. From Rodney Rogers to Alonzo Mourning to Eddie Griffin to Clifford Robinson, his free agents have consistently underwhelmed. His draft picks have been less than scintillating as well, with the selection of Antoine Wright ahead of Danny Granger in 2005 being particularly galling.

But it’s the subtle off-season moves that structure the end of the roster where Thorn’s struggles have been greatest. New Jersey’s second unit has been an open sore the past few years, partly due to financial constraints imposed by carrying three maximum contracts but mostly because the Nets have been poor at identifying inexpensive players who can make a contribution.

One notable exception to that trend came a year ago in the form of Mikki Moore. He filled in spectacularly well after Nenad Krstic’s knee injury a year ago — after the Nets acquired him before the season from Seattle for just a second-round pick in 2009. Alas, Moore was a glorious fluke — a 31-year-old who never played that well before and never will again — and moreover, he’s just flown the coop. Moore signed a three-year deal with Sacramento this week, leaving the Nets once again scrambling for frontcourt help.

I wrote a few days ago that it would be a mistake for the Nets to replace Moore with the heavyfooted veteran Jamaal Magloire … so as you probably expect, I’m very disappointed by New Jersey’s move to give Magloire a one-year deal for $4 million. Yes, there’s little risk since it’s a one-year deal, but the guy has declined so rapidly in the past three years that one has to wonder if he’s going to be a poor man’s Jason Collins … without the defense.

But the part that gets me really riled up is a second move Thorn made this week, one that was lost in the shuffle of the Magloire signing — the decision to waive Hassan Adams. At the margin, I can understand what Thorn is thinking here. He wanted to keep the team under the luxury tax threshold. After signing Magloire, the only way to that was to waive Adams and Clifford Robinson.

Although Adams was slated to make only $687,500 this year, which is pocket change in NBA terms, the real cost to the Nets would have been much higher because that salary — which would have become fully guaranteed as of July 15th — would have put the Nets over the tax. That costs the team not only the tax amount, but also the money redistributed to the other teams that are under the tax, so essentially the Nets saved about $3 million by cutting Adams.

Of course, there was another way to dot his, and it’s called, “Don’t pay $4 million for Jamaal Magloire and then cut somebody who could be just as valuable.” That’s especially true when New Jersey could have kept Adams if the Magloire deal had been for $3.6 million instead of $4 million — was there really so much of a bidding war for this guy that this extra amount made the difference?

And yes, I realize size comes at a premium in the NBA, but signing a 7-foot stiff doesn’t require a big chunk of cash and that’s essentially the market New Jersey was picking through. Between Collins, Krstic, Josh Boone, Sean Williams, and Mile Ilic, the Nets weren’t lacking big bodies — they were lacking skilled big bodies. The addition of Magloire doesn’t change that.

To cut Adams in order to pull this move off seems shortsighted at best. I don’t want to overstate things here — he wasn’t going to be the next Dr. J or anything. But he was primed to be a very effective energy guy off the bench, essentially a 6-foot-4-inch version of the Knicks’ Renaldo Balkman. In his rookie year after he was New Jersey’s second-round choice in 2006, Adams shot 55.6% from the field and averaged an impressive-for-a-guard 6.1 rebounds per 40 minutes. He can’t shoot from outside, but his running and energy were effective enough that he still averaged a point every three minutes, which is decent production for a reserve.

All told, his Player Efficiency Rating (PER, my per-minute rating of a player’s statistical effectiveness) of 12.8 was solid for a reserve, especially one in his rookie season — and especially one competing with the likes of Wright (8.2) and Bernard Robinson (7.8) for playing time.

But don’t feel bad for Adams — some smart team will nab him real fast, probably for much more than the Nets were scheduled to pay him. Instead, feel bad for Kidd and Carter, who just lost one of the few potentially productive supporting players for this coming season.

And most of all feel bad for Nets fans, who now must lament that their team gave up their remaining space under the luxury tax to sign a fading backup center and effectively traded up one of their most promising young players to make the deal. It’s just the latest glaring example of Thorn’s inability to surround his stars with the talent necessary to return this team to the conference’s elite, and I’m not sure he can make enough big-picture moves to undo the damage.

jhollinger@nysun.com