Taking Henry Ellenson with the 18th pick made Stan Van Gundy happy on draft night because the scouting arm of the front office he assembled told him he should be.

It was confirmed for him the following morning, when he watched the Ellenson college videotape he’d been told to largely ignore during the predraft process because there was no way Ellenson would last that long.

In less than two weeks of training camp, “happy” has become something closer to “ecstatic.”

“He’s a gooood basketball player,” Van Gundy said as the Pistons prepared for this week’s preseason opener in Brooklyn, which ended in a 101-94 loss and marked Ellenson’s debut with two points and three rebounds in six minutes. “He’s got a chance to be really, really special.”

Before you blow by that last comment, understand this about Stan Van Gundy. He’s been in the NBA for two decades. He’s seen waves of first-round draft picks come and go. He’s as media savvy as any coach who’s ever walked an NBA sideline. He doesn’t hand out “really, really special” bouquets like business cards. He grasps the implications of such buildup.

He’s just that sure that in Ellenson, the Pistons have themselves a player.

“He’s getting better every day. He’s got a tremendous ability to focus and learn. A lot of guys work hard and they’re receptive and respectful, but it’s hard for them – or it’s slower, at least – to actually be able to incorporate what you’re doing into their game. He’s got a remarkable ability to assimilate what’s going on and go out and use it. He’s getting better and better and better.”

So much so that Van Gundy already is anticipating the day a rookie behind both Tobias Harris and Jon Leuer at power forward and a break-glass-in-case-of-emergency option at center behind Andre Drummond, Aron Baynes, Boban Marjanovic and Leuer will force some decisions on the organization.

“I know this: I wouldn’t have a problem putting him on the floor right now. He’s just not ahead of those other guys – nor should he be, at this point, less than two weeks into his NBA career. But he’s good enough that eventually – whether it’s sometime this year or early next year – he’s going to force us to think about how we use our frontcourt rotation. Because he’s pretty damn good.”

Van Gundy has been struck by how competitive Ellenson, who measured 6-foot-11½ at the NBA draft combine last spring, has been in Pistons scrimmages against players who are all well ahead of him in physical maturity. The Pistons are suddenly a very big, very physical team with Drummond, Baynes, Marjanovic and Leuer. Their edge in strength and experience gives them defensive advantages that Ellenson can’t yet match.

“His challenge is on the defensive end,” Van Gundy concedes. “But even there, I see improvement in terms of the team defense and being able to make his calls, his pick-and-roll coverage and other stuff. Individually, both in the post and on the perimeter, is going to be his challenge.”

Ellenson, though he hasn’t felt overwhelmed as a 19-year-old in a decidedly grown man’s world, concedes the adjustment of not having a physical advantage two years removed from playing small-school basketball in northwestern Wisconsin.

“It’s fun going against those guys and playing with them because I’ve never played with size like that before,” he said. “Maybe like one on a team but now you have three other guys – not as tall as me, except Boban – but playing with big guys at that size is a lot of fun. It’s been great for me.”

His defense at Marquette had two possibilities – “left” and “right” – and now he’s dealing with a dizzying array of calls and must make in-the-moment decisions and bark out calls to perimeter defenders.

“Out here you have a whole bunch of different things you can do with the ballhandler off the screen and depends on who you’re playing,” he said. “We have quite a few calls and you’ve got to know them quick. That’s something I think that’s probably my biggest adjustment, just making different calls and getting ’em out early and loud. Because if you’re not saying it quick enough, your teammate is getting hit. I know they don’t appreciate that, so it’s something you’re got to learn and I think it’s been going good.”

Van Gundy sees a day not far away when Ellenson is going to cause at least as many defensive challenges as he faces. You don’t often see big men – let alone teenaged big men – who so effortlessly handle the ball. Ellenson is deft at executing dribble handoffs or passing off the dribble, a skill made more effective by a perimeter shot already improved over a summer of coaching and practice.

“I think our front line is pretty good and so every day he’s playing against Marcus (Morris), Tobias and Jon,” Van Gundy said. “And he’s a hard guy to guard because he can shoot the ball, he can put it on the floor, he can pass off the dribble. We’re really, really happy with him and the last couple of days I’ve seen him getting better defensively.”

For every bit of coaching Van Gundy and his staff are giving Ellenson, they’re also observing to gauge all that he’s capable of doing before deciding what to harness. Another unique skill of Ellenson’s is grabbing defensive rebounds and leading the fast break – again, not the thing you expect of a virtual 7-foot teen.

“He can do that,” Van Gundy nodded. “He can put it on the floor. We’ll have to get more of a feel for his decision-making process if that’s something we want to happen. But for now, I want to see it, so I’m not taking it away from him. His ability to put the ball on the floor, in fact, that’s probably where he’s really special. There just aren’t that many guys his size who can handle the ball and make plays off the dribble like he can.”

It might be a while before Pistons fans get to see all of that. Stan Van Gundy expects it’ll be worth the wait.