The Rangers’ core never has been more in question, and that includes Derek Stepan.

The Blueshirts’ alternate captain and de facto top center did not mince words when evaluating his own postseason, a harsh evaluation after his team’s season ended with a 4-2 loss to the Senators in Game 6 of the second round Tuesday night at the Garden.

“Individually, I’m disappointed and ashamed and flat-out embarrassed,” Stepan said. “It kills me I was not able to find my game. It is what it is, just have to live with it.”

Stepan joined the Rangers for the start of the 2010-11 season after being a second-round pick (No. 51 overall) in the 2008 draft. He has been a model teammate and a model of consistency — even if it has been unspectacular consistency. But he made many uncharacteristic plays during this postseason, turning the puck over while hesitant to make plays in the offensive zone when scoring chances were available.

“It’s confidence for me,” he said. “Confidence in making the right plays. Just struggled to do it, all playoff long.”

Stepan will turn 27 on June 18, and he has four more years left on his deal that carries a hefty $6.5 million annual salary-cap hit.

The odds of general manager Jeff Gorton being able to move him for a commensurate return is unlikely. The best-case scenario might be a deal similar to when Gorton shipped Derick Brassard and his $5 million cap hit up to Ottawa last summer in the deal that brought back the younger Mika Zibanejad, set to be a restricted free agent.

Yet that also would be dumping a player who has meant so much to the organization during its recent runs to two conference finals and one Stanley Cup final.

After Tuesday’s season-ending loss, coach Alain Vigneault was asked to evaluate Stepan’s game — and he knew it was the inappropriate time to do so.

“I’m not going to get into personal evaluations,” Vigneault said. “It’s an emotional and tough loss for everybody — for us and our fans. We’re going to take a little bit of time here and do this another day.”

Stepan finished the regular season with 17 goals and 55 points in 81 games, right in line with his career averages. He had two goals — one shorthanded — and six points in 12 postseason games, but it just wasn’t enough to help move his Rangers forward.

Now part of Gorton’s evaluation is figuring out where Stepan fits into their big picture. It might be just where he is now, but hardly anything is set in stone.

“I’m real proud of this group,” Stepan said. “They did a lot of good things. It’s never fun losing your last game of the series.”