Struggling to find his game, then hit with a slight injury, and there was Chris Kreider on Wednesday afternoon, skating as no more than an extra at Rangers’ practice, his top-six role now seemingly in the hands of J.T. Miller.

Kreider did not play in Monday’s 4-3 overtime win against the Penguins at the Garden, and the lone stated reason was he woke up suffering from neck spasms as a result of an odd collision with Carl Hagelin at the preceding practice. What went unsaid by coach Alain Vigneault was that maybe the injury came at a convenient time for Kreider to sit and watch one, as his frustration not only has manifested itself in the occasional slammed stick, but also has begun to drag his game deeper into the depths of a funk.

So it was Miller, the mercurial 21-year-old who has struggled to establish the fact he’s a full-time NHL player despite a plethora of opportunities, coming up from three games as a fourth-liner to fill Kreider’s spot. Miller has shifted from center to wing, playing a physical and straightforward game, and it seems to be just what the coaches want — really, just what the coaches were looking for from Kreider.

“I’ve been here through Millsy, the first couple years here, and you can see it — each time he’s here, he has more confidence than the last time he was here,” said center Derek Stepan, who was between Miller and Marty St. Louis on Monday. “He’s certainly learning the game.He’s learning down in Hartford and then he comes up here and he’s really applying it to the game. He’s been able to get the mental aspect of the game down, and pick up some things along the way.”

That “mental aspect” is what Miller himself labeled as maturity during training camp, out of which heMiller made the team out of training camp only to be demoted three games into the regular season. He was called back up just before the Nov. 29 game against the Flyers, and has two goals in the four games he has played.

“When I get sent down, I don’t want to take it as a negative all the time,” Miller said. “You can use it as motivation, I guess, to try to get back up. It’s only been four games, so I’m trying to keep the same attitude.”

It would be a surprise if a physical ailment was what kept Kreider out of Saturday’s game against the Canucks in Vancouver, the beginning of a four-game road trip. He practiced fully on Wednesday — albeit as an eighth defenseman — while the fourth line, the most likely other landing spot, remained intact with Tanner Glass, Dom Moore and Jesper Fast.

Kreider didn’t speak to the media, and Vigneault was in Montreal, along with general manager Glen Sather, to attend the funeral of hockey legend Jean Beliveau. The coach was set to return to New York on Wednesday night, then fly with the team to Vancouver on Thursday, where they would practice on Friday before the game.

There he might decide Kreider is fully healthy, and put him back in his regular spot next to Stepan and St. Louis. Yet on Wednesday, with assistant coach Scott Arniel running practice, they spent a long time working on the recently disappointing power play — and Kreider was on neither unit. Instead, it was Miller as the net-front presence on a second group, a position he never has played — not for the Rangers or for the Wolf Pack.

“Always like to have opportunities like that, with a good chance to see a lot of skill with the other guys,” Miller said. “I just have to go get my butt in front of the net whenever I get an opportunity.”

The opportunity for Miller is now as great as it has been in his career. If it’s at the expense of Kreider, well then so be it.

“The experience comes and you expect a little more out of yourself every day,” Miller said. “So the older I get, the more games I play, I expect more and I’ll be more confident.”

Anthony Duclair, 19, was not at practice. He was on his way to Toronto to join Team Canada for the upcoming World Junior Championships.