In the end, the Nets’ alleged “Big Three” came up mighty small.

And that, in turn, goes a long way toward explaining why at least one of those three — Jason Kidd, Richard Jefferson or Vince Carter — probably won’t be roaming the Swamp when fall rolls around.

New Jersey began this season thinking they had built the nucleus of a contending team. As I’ve argued all year, they were vastly overselling themselves, but it was amazing how durable the myth proved to be. Only after they closed their season last week with three straight fourth-quarter flameouts against Cleveland was it accepted beyond any reasonable doubt that the Kidd-Jefferson-Carter triumvirate needs either more help or a dramatic restructuring in order to contend for a championship.

To do nothing, at this point, seems unconscionable. What was so galling about the Nets’ performance against Cleveland was the totality of the offensive breakdown, something that shouldn’t happen with three perimeter players who are supposedly as talented as any trio in the league. The obvious conclusion here is that they’re not, and that they need more help.

Nothing underscored this more than the Nets’ fourth-quarter struggles, when the games tended to turn more into halfcourt struggles, which have been New Jersey’s sore spot throughout the Kidd era. Over the final three games in the Cleveland series, the Nets attempted 47 shots — and made six of them, for a splendid 12.8% shooting mark. Kidd and Jefferson combined to shoot 0-for-18, with Carter only a slightly more respectable 2-for-13.

Getting this trio more help isn’t really feasible with the team’s situation. The Nets are well over the salary cap, don’t have the kind of young players that would interest another franchise in a blockbuster deal (Marcus Williams and Josh Boone are supplemental parts, not centerpieces), and won’t have a high draft choice this year.

So to get better, New Jersey is left with three options: Trade Kidd, trade Carter, or trade Jefferson. The goal in each case would be to get more frontcourt help, both to eliminate the need to lean so heavily on the offensively useless Jason Collins, and to improve the Nets’ ineffective halfcourt game by adding more interior scoring.

Carter, who will be showing up for Game 6 any minute now, is the first domino because he can opt out of his contract this summer and become an unrestricted free agent. While the pickings are slim as far as destinations (only Charlotte has enough dough to pay him the maximum, though Orlando and Memphis could also get into the fray) the Nets still don’t want to lose a marquee player without compensation.

Carter can also extend his deal with the Nets between now and July 1, which presumably he’d only do if there were some assurances about the other players that would be joining him — i.e., Kidd. At 30, one would think he’d have little stomach for a rebuilding project, though that can be a positive too — he’d think real hard before signing on with Charlotte or Memphis.

Of course, the “trade Carter” camp is gaining wind after an unimpressive second-round series against Cleveland. He shot 35.7% and made a game-clinching turnover at the end of Game 4, and some have questioned his willingness to give up the rock to Bokie Nachbar in three different last-second situations during the postseason. Dealing Carter could be done either as a sign-and-trade after he opts out, or an “extend-and-trade” arrangement, and would probably bring back the most value.

That said, dealing one of the other two also has some merit. Consider Jefferson, who is the youngest of the three, but perhaps the most tradable. Although an ankle injury reduced his effectiveness for most of the season, Jefferson’s strong playoff performance — especially against Toronto in Round 1 — restored most of his trade value. Additionally, his contract is the least onerous of the three and his age makes him more desirable to more teams.

Moreover, Jefferson’s talents are mostly in transition, not in the halfcourt. His shaky long-range shooting isn’t doing any wonders for Carter, who was constantly hounded by extra defenders in the Cleveland series, and that’s especially problematic given that Kidd isn’t exactly the second coming of Reggie Miller either.

The third possibility is trading Kidd himself. Though he’s the face of the franchise and its unquestioned emotional leader, there’s more logic to dealing him than you may suspect. Kidd will be 35, and is coming off an outstanding postseason. In other words, his value is never going to be higher, and in fact in another year or two it may be dramatically lower. Considering the Nets nearly dealt Kidd to the Lakers in February, the scenario doesn’t seem terribly farfetched.

So which way should they go? I’d argue that the Nets should go one of two directions — depending in part on Carter’s whims and in part on their own willingness to spend some bucks.

The first one is what I call the “win now” strategy. This involves keeping Kidd, re-signing or (preferably) extending Carter and trading Jefferson. The idea would be to trade Jefferson for more frontcourt help, and then seek to fill his spot by signing a more capable shooter with the midlevel exception. This would also probably involve letting Mikki Moore walk as a free agent and re-signing Eddie House.

The upshot of this strategy is that the Nets would be doubling down on their bet to win a title with the Kidd-Carter combo. They’d have about a two-year window considering the ages of Kidd and Carter, after which they’d have a veteranladen team that would be likely to fade relatively quickly. They’d also have to be willing to spend more to bring in ancillary players that could make a realistic run at a title.

The other option is what I call the “dynamite” strategy. This involves dealing Carter AND Kidd, because there’s no point in doing one without doing the other. Trade Kidd and you end up with a young team surrounding a 30-year-old Carter who no longer has another veteran around to kick him in the rear when he starts loafing. Trade Carter and you take away the best scorer from a team that already had proven its inability to score in the halfcourt.

Either way it puts them farther from a title than they started, so at that point the obvious solution is to make a long-term play, build a new core around Jefferson, Nenad Krstic, and whatever pieces can be gleaned from the Kidd and Carter deals, and hope the kids gel relatively quickly.

Obviously, most Nets fans would prefer watching Kidd to watching kids, and if that’s the case it seems to me Jefferson is the odd man out. But after watching the Nets offense implode against Cleveland, the time for a change is long overdue. As it turns out, the Big Three wasn’t nearly big enough to make up for this team’s other shortcomings.

jhollinger@nysun.com