Sure, there was a blockbuster trade on draft night. Just not the one we expected.

Instead of the much-discussed deals of Jermaine O’Neal or Kevin Garnett, it was the Seattle Super-Sonics’ Ray Allen and the Trail Blazers’ Zach Randolph who found new homes on yesterday evening. And even more surprisingly, the Knicks were one of the teams doing the acquiring.

New York agreed in principle to a deal that would acquire Portland’s left-handed low-post powerhouse, along with guards Dan Dickau and Fred Jones, in exchange for guard Steve Francis and forward Channing Frye.

On talent, the Knicks made out like bandits. Randolph is a fantastic low-post scorer, but also has the touch to step outside as far as 20 foot and loft in rainbow jumpers — something he’ll need to do since he’s sharing space with Eddy Curry. And unlike Curry, he’s also a beast on the boards. For the Knicks to acquire him in exchange for two utterly disposable commodities is a huge surprise.

It also speaks volumes, however, to how much Portland wanted to get rid of Randolph. Though his talent is undeniable, he’s also had several scrapes with the law and he’s overpaid — he has four years and $61 million left on his deal, the kind of phrase that’s become familiar to Knicks fans in the Isiah Thomas era.

Additionally, Randolph is a slowfooted, lethargic defender. Pairing him with Curry — another slowfooted, lethargic defender — raises some obvious red flags, particularly since the Knicks defended poorly a year ago. Combining the two would create what is almost certainly the worst defensive frontcourt in basketball.

The trade may not be completed for a few days, but despite my reservations about Randolph’s defense, demeanor and salary, it has to be considered a huge coup for New York. They get a star essentially for nothing, and this deal should launch them into the playoff race.

But they’ll need that upgrade to keep up in the suddenly fierce Atlantic, thanks to what happened earlier in the evening. Seattle surprised everyone by dealing All-Star guard Ray Allen and a secondround pick to the Knicks’ rivals to the north, the Boston Celtics, and getting the fifth overall pick, guard Delonte West, and forward Wally Szczerbiak in return. Then they threw another monkey wrench into the proceedings by taking Georgetown forward Jeff Green with the pick — rather than the consensus no. 5, Chinese 7-footer Yi Jianlian.

On Boston’s end, the Allen deal is a signal that the Celtics are trying to contend immediately. And despite a horrible campaign a year ago, they’re closer than you think. The combo of Allen, Paul Pierce and rising post star Al Jefferson is a powerful triumvirate — certainly it trumps the Nets’ big three — and now Boston is in a position to lure some veteran role players with its salary cap exceptions this summer.

Meanwhile, new Sonics GM Sam Presti sent a loud signal that his team is changing gears. For several years Seattle has been an offensive-minded team built around Allen and forward Rashard Lewis, but now Allen is gone and Lewis is likely to follow – he’s a free agent who will probably be in a new locale next fall.

That sets up Seattle to head in a new direction — perhaps literally, as they may relocate after the season. And they have a great centerpiece to do it, as second overall pick Kevin Durant is a superstar in the making. The obvious idea is to surround him with complentary players and Green fits the bill — he’s an exquisite passer and can defend multiple positions. My only question is whether Green is the kind of star-caliber player a team wants to take that high in the draft.

Locally, the Nets also were in trade talks. New Jersey was rumored to be working on a deal that would send Richard Jefferson and Nenad Krstic to Indiana in exchange for forward Jermaine O’Neal, giving the Nets a longsought post presence to complement Jason Kidd and Vince Carter on the perimeter. Boston’s pick-up of Allen may have added some more urgency to that pursuit, but nothing happened on draft night.

In the draft itself, both teams pulled the trigger on first-round picks. New Jersey took a flier on Boston College center Sean Williams at no. 17 — an outstanding shot-blocker with a Mikki Moore-type build who was kicked off his college team for repeated marijuana use. The Nets are desperate enough for size that they gambled on his talent anyway.

At no. 23, the Knicks took DePaul sophomore forward Wilson Chandler, a 6–8 Renaldo Balkman clone who may have trouble earning a lot of minutes at the suddenly crowded small forward spot next season.

There were few surprises at the top of the draft. As expected, Portland tabbed Ohio State big man Greg Oden with the first overall pick, providing a linchpin for one of the league’s most promising franchises. After Seattle took Durant, the Atlanta Hawks nabbed Florida forward Al Horford third and Memphis grabbed Ohio State guard Mike Conley fourth.

Three Florida Gators — Horford, Corey Brewer, and Joakim Noah — were among the top nine picks, the first time three teammates have been selected that high. Brewer went 7th to Minnesota, which may have been a reach, but this hardly surprised anyone given that the T’wolves are the league’s worstmanaged team. Noah went 9th to Chicago, and showed off a retro suit complete with bow tie at the podium that will feature prominently in draft archive footage for many years to come.

In between those two, Michael Jordan — surprise — took a North Carolina guy, Brandan Wright. Wright is the fourth Tar Heel on his roster, joining Sean May, Raymond Felton, and Jeff McInnis.

Six of the first 12 picks were freshmen, a testament to the league’s new policy of restricting high-school players from turning pro. The biggest surprise was the sixth, forward Thaddeous Young of Georgia Tech, who Philadelphia selected at no. 12 — most observers had him going later, but he’s a bigtime inside-outside threat who should have an outstanding career.

jhollinger@nysun.com