It’s an annual event in New Jersey: the midseason surge into quasi-contention that leaves everyone confused about what to do next. The Nets entered last night’s game against the Bobcats feeling as good as they have all season. A five-game winning streak put them in fifth place in the Eastern Conference, and their offense suddenly looks far more capable than the anemic outfit that took the floor over the first month of the season.

The key, undoubtedly, was coach Lawrence Frank’s decision to insert youngsters Josh Boone and Sean Williams as the new starting frontcourt. New Jersey is 7–2 since the switch, and they’ve cleared 100 points in six of the nine contests — after only doing it six times in the first 23 games.

Of course, this move succeeded as much for what Boone and Williams aren’t as for what they are. The three players they replaced — Jason Collins, Jamaal Magloire, and Malik Allen — were some of the least productive frontcourt players in the league, so the switch almost couldn’t help but improve the team. It gives the Nets a new dimension, because their frontcourt players can finish what the perimeter trio starts.

“It allowed us to complement Jason [Kidd]’s play better,” Frank said in an interview Saturday night. “Jason’s greatest strength obviously is pushing the ball, and even though those guys haven’t played great every night, at least it gives us the foundation that we have someone to run with him. And it also puts pressure on our other guys to run as well.”

Indeed, the Nets ran up 113 points in Atlanta on Saturday — a season high — thanks in part to the fact that the interior guys are part of the offense again. Boone and Williams combined for 32 points and 17 rebounds in that game, production Collins and Allen would need a month to match. In nine games since the switch, Boone is averaging 10.3 points and 8.3 rebounds, while Williams is getting 8.0 points, 6.6 boards, and 2.4 blocks.

“With our team, because of our perimeter players, if you can roll, catch, and finish, à la Mikki Moore or Nenad Krstic, you’ll get 10 points a game,” Frank said.

Having finally found two guys who can finish in the paint, the Nets’ offense has awakened from its early-season doldrums. Not only are the kids providing added offense, they’re also taking the heat off of Vince Carter and Richard Jefferson to score on every play — those two now have the luxury of being passers if the defense crowds them.

As usual, Frank deserves credit for pulling the trigger on the move — one he made even though it goes against most of his coaching instincts. He tried not to overreact at the start of the season and went with the status quo for as long as he could before it became obvious that a shake-up was necessary. And you know there’s still a part of him that’s going crazy watching Boone and Williams learn on the fly.

“The stats are better. It hasn’t always been an execution standpoint where we’ve been better,” he noted. But those who give can also take away. For every mistake by Williams and Boone, they erase a teammate’s with their shot blocking — a skill that had been glaringly absent in the early part of the season.

And with added minutes, the young ones are learning faster. Boone provided a good example on Saturday while guarding Atlanta’s star forward, Josh Smith. After the quicker Smith tormented him during the first half, Boone adjusted, took away Smith’s dominant left hand, and got a key block against him in crunch time.

“Josh is a very cerebral player,” Frank said. “He’s really taken advantage of the opportunity.”

Thanks to this resurgence, the Nets are as optimistic as they’ve been all season. With Nenad Krstic slated to return next month, Marcus Williams back in the lineup, a solid and productive starting five, and Bostjan Nachbar emerging from an early-season slump, a top-5 seed in the East suddenly seems like a real possibility.

This is good news, of course. But it’s going to force them to make some hard decisions at the trade deadline.

If the Nets had kept sleepwalking the way they did in November, then team president Rod Thorn would have an easy call to make come February — break out the dynamite, start taking calls for Kidd and Carter, and rebuild around the kids that were left.

But with the Nets making a playoff push, the calculus is now more difficult. Much as the Nets did a year ago, when they dangled Jason Kidd in front of the Lakers before hanging on to him, they may spend this trading season torturing themselves over whether to start the rebuilding for their move to Brooklyn in 2010, or keep hammering away with this group.

Since even the briefest winning streaks can cause a disconnect from reality, it’s important to remember that despite all the recent good news, New Jersey still has some big-picture stats that are quite troubling. They’ve given up 135 points more than they’ve scored this season, and have kept their heads above water by being unusually fortunate in close games — they’re 12–3 in contests decided by five points or less. But a scoring margin like that usually lands a team several games south of .500 before long.

Additionally, the schedule is going to turn against them. They’ve played five more home games than road games so far, and have played only 10 of their 30 scheduled games against the tougher Western Conference.

Finally, the injury bug can swing both ways. While the return of a healthy Krstic would undoubtedly make this a stronger team, the opposite would happen if Jefferson or Carter were to turn an ankle or tweak a hammy — hardly a rare event around these parts in recent seasons.

Where does that leave us? Most likely with a middling team that has two 30-something stars, one that has no chance whatsoever of challenging Boston and Detroit at the top of the East.

And so the question becomes, is that good enough? Thorn will have the next month to watch his team and decide.

In the meantime, one thing is for sure: The fact that we’re even asking the question is a huge improvement from nine games ago. And for that, Frank’s frontcourt shakeup deserves the lion’s share of the credit.

jhollinger@nysun.com