NBA

Up to D’Antoni to solve Knicks’ mystery mix

DALLAS — We have reached the crossroads of Mike D’Antoni’s time as the Knicks’ head coach, halfway through this seminal four-game road trip. The Knicks are a jigsaw puzzle of both promise and petulance, of hope and haplessness.

They are a jumbled mess and an improvisational curiosity. They are entertainingly frustrating and frustratingly entertaining, they are unpredictable, they are impossible to write off yet impossible to stand behind.

Mostly, after this 95-85 loss to the Mavericks, they are two games south of .500 for the first time in three weeks, entrenched in eighth place in the Eastern Conference when they were supposed to be on a mission for sixth … or higher. They are a roster of moving parts and square pegs trying too often to fit into round holes.

“We have the talent to compete,” Amar’e Stoudemire said last night. “You can’t say we don’t have enough guys.”

Sometimes, in truth, it seems they have too many guys, too many options and too many combinations. The rule is supposed to be that you can never have too much talent.

D’Antoni is disproving that credo.

“We have to find combinations that work,” he said yesterday, and he’s right, but the fact is all that does is complicate matters further for him. Yesterday, those combinations excluded Carmelo Anthony, who was mostly a spectator as the Knicks turned 66-47 down into 78-77 up.

The depth that has allowed them to come back in three straight games — including a win last week against the Cavaliers — has complicated the Knicks’ most basic mission. We were treated to the very worst of J.R. Smith last night, for example — poor shot selection, worse decision making, and a technical foul thrown in at no extra charge — and yet D’Antoni still played him 14 eventful minutes.

Stoudemire, playing his best game in weeks, capped the Knicks’ comeback with a driving shot with just under five minutes to go, then watched as the Minutemen reserves, one-by-one, were replaced by the starters. The one-point lead quickly reverted to a 10-point deficit. Coincidence? Maybe. Probably. Basketball is a game of cycles and a game of runs.

But that’s where D’Antoni has to adapt and adjust and study how to make all of these parts fit, how to make them functional. It would help if he could have a reasonable facsimile of Anthony at his best, because that version of Melo is the kind of talent you don’t worry about, who can play with anyone else and make them better. The version he got last night — 2-for-12 shooting, little explosion, alternately indifferent and ineffective — only adds to his complications.

The easy part for D’Antoni were those heady first few days of the Jeremy Lin Era, the Knicks decimated by injury and personal tragedy, shrinking the roster and limiting his options. There was the night he famously said of Lin, “I’m gonna ride him like friggin’ Secretariat,” but he could have been talking about his whole eight-man Iron Man rotation.

You can’t live that thin in the NBA, certainly not in the double-quick 66-game version of the schedule this year, but as the Knicks rattled off seven straight wins and clawed their way back to sea level at 15-15, it sure helped add layers to the story. It wasn’t just Lin cobbling together the resolve to keep the season from slipping away night after night. It was everyone.

It’s just that “everyone” was a lot smaller group then.

Now D’Antoni has options. He has talked about an 11-man rotation. He mixes and he matches, and sometimes the results are glorious: an 18-point turnaround late in Sunday’s game at Boston, that remarkable 20-point turnaround last night from 19 down with 19½ minutes left in the game to one up with 4:55 left in the fourth.

And sometimes the results are horrid. The Celtics outscored the Knicks by 27 in one awful stretch Sunday. The Mavs mostly toyed with the Knicks last night for three quarters.

The Knicks can look glorious. They can look ghastly. They can inspire crazy optimism. They can make you want to throw your remote control at the TV.

Maybe they can’t be corralled. Maybe they can’t be fixed. Before time runs out for good in Mike D’Antoni’s hourglass, it would be nice if he could find out for sure.

michael.vaccaro@nypost.com