"As far as shooting underhand or anything else, it's fair to say my discussion with Andre yesterday and the discussions [general manager] Jeff [Bower] and I have had and staff -- everything is on the table," Van Gundy said Thursday, according to The Detroit News.
Drummond shot 35.5 percent from the free throw line this season, a career-worst average, while going to the line a career-high 7.2 times per game. It was the worst free throw shooting season in NBA history.
The first-time All-Star in 2015-16 often spent the end of games on the bench, as his poor free throw shooting make him a detriment to the Pistons in clutch situations as teams targeted him for hacking fouls.
So the Pistons are going to look at all options to improve Drummond's free throw shooting and make him a viable threat at the end of games.
"It won't be a unilateral decision," Van Gundy said. "We'll do some research on some things and come up with what we think is a good approach, talk to Andre and see what he thinks and develop an approach going forward.
"We all know it's an important thing -- Andre more than any of us -- he's pretty open to anything. There's a lot of ways to attack this problem, and we'll all have a hand in it."
Part of the problem is taking practice success into games. Drummond says he shoots free throws "really good" outside of games, and Van Gundy estimates that his practice conversion rate at 65 percent.
"It's just hard, for whatever reason, to translate from the practice floor to the game," Van Gundy told ESPN's Tom Haberstroh. "Look, you're standing there by yourself, with the game stopped, and everybody's watching. Let's say a guy misses a jump shot. The play goes to the other end, and everyone's focused on what's happening there. But Andre's standing there at the free throw line, all everybody's talking about who's watching the game is his free throw shooting. It's hard. It's really hard."
Drummond is in line for a max contract extension this summer, and Pistons owner Tom Gores has said he is willing to give the 22-year-old big money.
The underhand free throw technique was popularized in the 1970s by Hall of Famer Rick Barry, who shot 90 percent from the free throw line in eight NBA seasons.
"The one thing we do know is the traditional approach and nothing else, of simply trying to correct mechanics and go in the gym and shoot a lot of free throws, has not worked," Van Gundy said Thursday. "So we've got to [try something] else. We've got to be a little more creative in how we approach it."
Information from ESPN's Nick Friedell contributed to this report.