Auburn Hills — It all started with a brazen declaration on draft night in 2015.

Stanley Johnson believed it then — and still does.

“I just think I’m the best player in the draft,” Johnson said, with unwavering confidence.

At 19, Johnson was the No. 8 overall pick by the Pistons, positioned to fulfill his claim with a blend of size and strength and an NBA-ready 6-foot-7 and 245 pounds.

His play in the Summer League and exhibitions last year provided hints he’d be a critical rotation player. And, Johnson’s performance his rookie season (8.1 points and 4.2 rebounds in 23.1 minutes) raised expectations for a potential breakout second year.

But, through five games this season, Johnson looks like a different player — and it’s not just the change to jersey No. 7 from No. 3. He has six points — total — and is shooting 13 percent (2-for-16) overall.

“What he’s battling more than anything else is buying in to the best way for him to play with where he is in his career right now,” Pistons coach StanVan Gundy said. “I’d like to think we have a staff of guys who have been around a long time and seen a lot of players and have an idea. Stanley right now needs to base his game on being a great defender, a rebounding perimeter guy.

“He can be as good a rebounder on the perimeter as anybody in the league. And he’s got to shoot open shots and make simple, solid plays.”

That hasn’t been easy for Johnson, who always has been the go-to player in high school in California , where he won four straight state championships, and one year at Arizona.

But the NBA isn’t like anything Johnson has seen. And Van Gundy and the Pistons staff is trying to position Johnson to adapt to being an all-around player with one strength first — then progressing to other areas.

“He has been a primary scorer his whole life and it’s tough for him to not play that way,” Van Gundy said. “Right now, that’s not the best way to play. I’m not trying to hold the guy back or limit him. What I’ve tried to point out to him is his development. The guy I’ve tried to use as an example with him who came in the league the same way is Jimmy Butler.”

Butler was a first-round pick of the Bulls and two-time All-Star — but didn’t start out that way. He was more of a defensive player, averaging 2.6 and 8.6 points his first two seasons, respectively, before honing his offensive game and averaging 20 points the last two years.

Johnson, however, knows it’s still early in his career, and he’s willing to do whatever it takes to succeed. It’s just a shift in mindset from being the go-to player to having a role pared down, at least initially, to defense and rebounding.

“(Accepting that role) is one of the things that as a professional, I have to be better at,” Johnson said. “I don’t think Stan is trying to take away from my game offensively at all but seeing the personality of the team, there has to be somebody to play defense.

“I’ve been the man all my life, but I’ve never been a player who would rather be the man than win games.”

Things have changed since 2015. Van Gundy traded for Marcus Morris, who became the starting small forward, Johnson’s position. At the trade deadline, they acquired another starter in Tobias Harris, who can play either forward spot.

That leaves Johnson to play mostly behind Kentavious Caldwell-Pope as the backup shooting guard, which isn’t his natural position.

As he adjusts, he’ll look to be more patient and let things come to him instead of forcing shots and playing outside his skill-set. Van Gundy harps on taking higher-percentage shots and that could be seeping into Johnson’s play this season.

“Right now, Stanley isn’t a primary scorer — he’s not. And playing like that simply leads him into low-percentage shots and turnovers, so he needs to base his game on different things,” Van Gundy said.

“The rest of it will come along.” @RodBeard