Even with injuries to their entire starting frontline pulling them back toward the play-in cutoff in the Eastern Conference, the Knicks are trying to remain prudent with Isaiah Hartenstein.

Since missing the final three games before the All-Star break due to his recurring left Achilles issue, the team’s fill-in starting center has averaged just 20.5 minutes over his past four appearances entering Sunday’s road game against the Cavaliers.

Hartenstein also sat out Tuesday’s game against the Pelicans — the second night of back-to-back games — for maintenance on the injury.

“I’m still just catching rhythm. I think that’s the biggest thing,” Hartenstein said. “I’m more comfortable and just catching my rhythm, I think that’s the biggest thing. [Thursday night] I felt like some stuff was a little slow, but that will all come with time, so that’s nothing I’m worried about right now.

“I feel it now a little bit. But that’s why you ramp it up because it will get better and better. … We don’t want to spike it up too much at this point. We have a good program in place. It’ll get better. That’s the good thing about it.”

The 25-year-old Hartenstein hasn’t been as productive since returning to the lineup as he had been during a 17-game stretch from the beginning of January until the game before he aggravated his injury Feb. 8 against the Mavericks.

Hartenstein had averaged 8.9 points, 12.5 rebounds and 1.6 blocked shots in more than 32 minutes per game as the Knicks posted a 15-2 run in that time.

But those numbers have dipped to 4.5 points, 5.8 boards and 0.5 blocks over his past four outings.

Hartenstein, who will be an unrestricted free agent this summer, added that the Knicks’ recent slide — a 4-8 mark in their past 12 games — prompted him to make himself available after the break, even if it’s been in a more limited role than he’d played before his most recent injury flare-up.

“I probably could have sat out a couple more weeks. But to me, I think we found a perfect medium where we’re ramping it up at a good time,” he said. “I just want to be here for the team.”

The 7-foot Hartenstein hasn’t logged more than 27 minutes in any of his past four games, and he was a minus-18 with six rebounds in 20 minutes in Thursday’s home loss to the Warriors.

Precious Achiuwa has served as the fill-in starter for injured All-Star Julius Randle (dislocated shoulder) at power forward, but he has also shifted to center when Hartenstein is on the bench.

Mitchell Robinson, who underwent ankle surgery in December, is out of the supportive boot — but he’s still waiting to be cleared for running and jumping, according to Knicks coach Tom Thibodeau.

Randle and OG Anunoby (elbow) could be closer to returning.

Both have resumed basketball activity, although they still are waiting to be cleared for contact.

The skidding Knicks entered Saturday’s league action 4.5 games out of the No. 2 playoff position in the East and just 1.5 games ahead of the No. 8 Pacers.

“There’s urgency. There’s urgency every single day. I feel like that was the main thing for me wanting to come back,” Hartenstein said. “Just to make sure I’m here for my team. I think that was the main thing why I felt like I needed to come and just help the team out.”

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Mock Drafts: Knicks Land UConn Guard Stephon Castle

The Big East Men’s Basketball Tournament is preparing to make its annual descent upon Madison Square Garden, which could give the New York Knicks a chance to scout some potential new talent.

A recent mock draft from Bleacher Report penned by Jonathan Wasserman has the Knicks dipping into the Big East talent pool, taking University of Connecticut shooting guard Stephon Castle at 23rd overall.

“Stephon Castle’s draft range sounds wide right now, with opinions varying on a scouting report that notes excellent physical tools, point-wing playmaking ability, strong defense and limited quickness, creation and shooting range,” Wasserman writes. “He could earn consideration from lottery teams willing to bet on and stay patient with a 6’6″ ball-handler who scores through contact, passes and defends.”

“He could also slip into the 20s if enough teams remain concerned by his shaky jumper and reliance on physicality.”

The freshman Castle is averaging 10.9 points per game on over 46 percent from the field, but his three-point shooting leaves a bit to be desired (just over 30 percent). Castle’s skillset fits head coach Tom Thibodeau’s style of coaching, as he defends very well and his 6-6, 215-pound frame makes him an imposing force inside at the guard spot. If the team were to draft him, he would fit in with the likes of Julius Randle when it comes to continuing the team’s shutdown defensive endeavors. Castle could get a greater look if OG Anunoby turns down his $19 million player option and tests the free agent market.