So perhaps this playoff thing isn’t in the cards after all. It appears the Atlanta Hawks don’t intend to lose again — Monday night’s blowout of Memphis made it four straight wins — and if that trend continues there’s nothing the Nets can do about it. The fact is they’ve already lost far more games (43, to be exact) than any worthy playoff team should, so they have only themselves to blame for not qualifying.

Nonetheless, the conclusion of this season is important for much more than just a desperate push for the playoffs. New Jersey essentially has a new team, and it’s likely to undergo some more major changes before the rebuilding is complete. Now is the time to start looking at who should be part of the future and who shouldn’t. Let’s start with the obvious. Every good player under 25 should be an important part of the team’s plans, because the Nets’ only path back to contention is to increase its talent base from where it is now.

Or maybe it’s the not-so-obvious. Because while that list includes the usual suspects — Devin Harris and Josh Boone, most notably — it also includes a couple of guys who have fallen out of favor recently.

I’m speaking of the two Williamses, Marcus and Sean. Both are first-round picks from schools in the Northeast, both had issues in college (Marcus with hot laptops, Sean with flammable herbs), and both have been in Lawrence Frank’s doghouse for much of this season. Marcus’s stint came in the first half of the season, as he only saw 10.1 minutes per game before the All-Star break, while Sean’s came later — he’s only played 10.5 per game since the break.

In each case, Frank had good reasons. Marcus, for instance, is the classic young NBA player in some ways — talented enough to be a decent player someday, but too headstrong to realize he’s not nearly as good as he thinks he is. There’s a lot to pick on here: He doesn’t defend, he needs to get into better shape, he takes too many bad chances with the ball, and his delusions of scoring grandeur subvert a genuine talent for passing.

In particular, his penchant for throwing the ball to the other team is a major red flag. Williams turns the ball over on 14.6% of his possessions, the second-worst rate among NBA point guards. (Ready for the punch line? Darrell Armstrong is the worst.)

Combine it with his 38.8% shooting mark from the floor — um, remind us again why he’s shooting so much? — and it’s clear Williams has a long, long way to go to be a quality NBA point guard.

With Harris around, he may not be in the Nets’ long-term plans in the traditional sense. But that’s where New Jersey can offer Marcus a certain kind of bargain — basically, his only chance of playing a starter’s minutes is for the Nets to trade him someplace with an opening.

And the only way for that to happen is for Williams to toe the company line, subvert his ego, and play well in his limited playing time behind Harris. He has the ability to do this, believe it or not. He just needs to come to terms with the fact that he’s not The Man.

Whether it’s this summer or next season, that should be the Nets’ endgame with Williams. But it only works if they get him on board. The easy way out would be to dismiss Williams as a failure and sign some well-traveled veteran for the minimum to take his place over the summer. The harder but more rewarding path is to turn Williams into a player and then use that asset in a swap for help at a position where the Nets are more shorthanded.

The Nets are in a similar bind with Sean Williams. With him, the problem isn’t with his attitude as much as his aptitude — he keeps blowing coverages because he’s been slow to learn the team’s defensive schemes, and that’s made coach Lawrence Frank reluctant to play him.

But ultimately, Williams is their best chance at someday becoming a decent defensive team. The Nets rank 21st in Defensive Efficiency (my measure of a team’s points allowed per 100 possessions), and that’s with Jason Kidd and Jason Collins playing half the season. The results have been even worse since mid-season, when the Nets changed their identity to become a more offensive team.

In particular, the Nets struggle to block shots. New Jersey ranks only 17th in blocks, and if you subtract the 1.5 per game from Williams — which the Nets have effectively done of late — then the only team they’re ahead of is the Knicks. Of the current regulars, only DeSagana Diop is a threat to reject an opponent’s delivery, and his offensive limitations preclude his being more than a 10-minute-per-night solution.

That’s where Williams comes in. Though undersized for an NBA frontcourt player at 6 feet, 8 inches, 220 lbs., he possesses a knack for shot-blocking that few in the league can match. He averages a swat every 11.8 minutes, the fifth-best rate in the league; one wonders if he can increase that haul once he gets the knack of NBA rotations and weak-side help.

Nobody is suggesting he replace Boone or Nenad Krstic as a longterm starter. But bringing his shot-blocking skill off the bench could give the team a big lift, especially since Williams is hardly one-dimensional — he also averages 12.9 points and 10.4 boards per 40 minutes on 52.1% shooting.

That sure seems like a better alternative than the current system, where Boki Nachbar is essentially the third big man in the rotation while Boone and Krstic are the only true frontcourt players seeing major minutes (though Diop gets his token scraps).

If the Hawks run away from New Jersey in the race for the no. 8 seed, so be it. The Nets still have plenty of projects to busy themselves with — both over the final weeks of the season and during the summer — to prepare for the post-Kidd future. Marcus and Sean Williams may be bit players at the moment, but, looking ahead, they’re two of the most important pieces of that future.

jhollinger@nysun.com