After Andre Drummond’s 2016 season, which included an All-Star selection, many expected that he would continue his ascension.

It’s just not that easy.

Drummond led the league in rebounding that year and returned last season with a good year, but not to the same standard he had set. With pick-and-roll partner Reggie Jackson sidelined for 30 games, Drummond still posted another solid season, with 13.6 points and 13.8 rebounds.

One of the biggest keys to the Pistons’ improvement next year will be not only reestablishing the chemistry with Jackson, but continuing Drummond’s own individual improvement.

“He’s already historically one of the best rebounders this league has ever seen. He’s got a leg up on being a very good player and was an All-Star at 23,” coach Stan Van Gundy said Monday on “The Drive with Jack Show” on 92.1 FM in Lansing. “Andre’s combination of size and athleticism make him very difficult for an opponent to deal with.

“With him, it’s having a better motor, to come every night with tremendous energy, getting up and down the floor, defending at a higher level on a consistent basis. That’s really it — it’s playing harder, more consistently and Andre has taken some steps this summer to make sure he does that.”

Many fans were disappointed in Drummond’s performance last season, pointing to his continuing free-throw woes and impatience with him not taking bigger strides in his overall improvement.

After having sinus surgery, Drummond took some time away from basketball to recover. Since then, he’s played in some Drew League games in Los Angeles and shown that he’s still playing at a high level. Van Gundy said Drummond has lost 20 pounds and worked on his conditioning.

The bigger — and more immediate — impact for Drummond could be on the defensive end, where his energy and effort could provide a lift.

“We really have tried to impress upon him how important the defensive end of the floor is. He’s got all the tools to be a first-team All-Defense type of guy,” Van Gundy said. “He can really move his feet, guard pick-and-roll and he’s big enough and strong enough to guard his guy one-on-one in the post.

“There’s nothing holding him back from being a great defensive player. If he takes that pride in that, we go a long way toward being a better team.”

Along with the defensive improvement, the inevitable questions about Drummond’s free throws — up from 36 to 39 percent last season — still are a big issue to be addressed. He worked on some new techniques last season, including walking back to center court between free-throw attempts.

The NBA changed a rule this summer, outlawing that practice, giving a delay-of-game warning for a free-throw shooter who goes beyond the 3-point line between attempts. That’ll send Drummond back to the drawing board to figure out a solution.

Van Gundy has coached in similar scenarios with Shaquille O’Neal and Dwight Howard, so trying to deal with it with Drummond is nothing different.

“Obviously, there’s some technique improvement that has to go on. My experience with those guys and the biggest thing to overcome is the mental part and the confidence part,” Van Gundy said. “You’re talking about three guys who are great talents and players and have so much success in every part of the game and have this one thing they struggle with… To go to the line with a true confidence and think the ball is going to go in the basket. It’s a hard thing. Do I think he’s capable of shooting in that 50-55-percent range? Absolutely, but to overcome the mental part of it will not be an easy thing.”