CAMDEN, N.J. — Al Horford’s question came with a laugh and a smile as he walked down the sideline of the west court in the 76ers’ practice facility Wednesday afternoon.

“What are you doing here?” he said. “We don’t play for two weeks.”

After the handshake and taking a seat, it was time for the real question.

What are you doing here?

“I’m here looking for that championship,” said a still-grinning Horford, who cut off talks with the Celtics in June and bolted for more money and what he believes is a better basketball situation with Philadelphia. “Looking for that championship.”

Contract aside — and that was not an insignificant consideration — if anything should sting back in Boston it’s that Al Horford looked at the Sixers and the Celtics on his hoop GPS and calculated the former were closer to a title.

It was a move that caught Boston management off guard to a degree. Horford was destined to opt out of the final year of the free agent deal he signed with the Celts in 2016, but he and his representation wanted to work with the club on a longer term pact to stay. But obviously the playing field changed at some point before the draft, and Horford knew he had a better ace up his sleeve. (And let’s not even dare to invoke the concept of tampering when it’s been an accepted part of NBA business — or do you think the Celtics did all that negotiating with Kemba Walker in the moments after the moratorium ended?)

Nothing should have been taken for granted around the Shamrock A.C. after the utterly underachieving season of 2018-19.

“Well, after last year ended, we were all disappointed with how everything went. I took some steps back, looking at what direction the franchise was heading and what was going,” Horford said. “And we all kind of felt that Kyrie (Irving) was going to leave. It was like, maybe he’ll stay, but then it was, nah, he’s probably going to leave just based on how everything was.

“And then I’m looking at my career and myself and the years that I have left. There were certain things that we wanted to accomplish as a team and things that we needed to make that happen. We got all those pieces last year, but it didn’t happen for us, and moving forward I didn’t know if it was going to be a two-year wait or whatever it was going to be. It was that and the financial reasons. When we started with the team trying to come up with things and we couldn’t agree on certain numbers, that’s when I decided, you know what, I’m going to have to open my free agency. I believe not only that I am worth a certain amount of money, but also I want to be in a position that I have a really good opportunity to win now. You know, my window is now. That’s how I feel.”

It originally was thought the Celtics and Horford were heading to a three-year deal, but a fourth season was on the table by the end. Things just didn’t add up, and once the Celts got wind that their big man had a better offer elsewhere, it was over. Horford wound up with four years at a total of $109 million ($97 million of it guaranteed) here.

“In their eyes, I feel that they did the best that they could and what made sense to them,” he said. “And obviously, you know, I feel like they’ve always made a point of my age — and I understand that, me being 33 years old. But they did what they felt was best for them and what makes sense for them. And it was hard, because I felt like I was really invested and really into Boston and what it meant to be a Celtic. But as hard as it was, I had to really think it through. I couldn’t go with …”

At this point, he tapped his hand on the left side of his chest. There should be no doubt that all of his heart was in Boston for his time there and that leaving wasn’t a choice he thought he’d have to make. But the heart he tapped was resting beneath a 76ers practice jersey.

“I had to think about what made sense for me and some of the things that I wanted to accomplish,” Horford said. “They were three really good years for me there, but we just fell short of that goal of raising that banner. I had to make a head-on decision, and it came down to the opportunity for me to compete for a championship, but also to maximize financially.”

As far as on the court, it’s certain Horford wasn’t interested in playing another hand from the same deck. I asked him if his decision would have been different if Irving had remained.

“I’m not sure that has anything to do with it for me,” Horford said. “I just think that if Kyrie would have stayed, I don’t know if it would have worked. There would have had to be some major changes as far as players, because it was just clear that the group that we had just wasn’t going to be able to coexist.”

And what about if he’d known Kemba Walker was coming. Horford paused.

“I don’t want to get caught up in the past,” he said, “but, yeah, that would have been totally different.”

Just as they are different here. He has moved on. He likes what he’s seen from the Sixers, and he’s happy that, with Joel Embiid, he’ll get more of a chance to play power forward and less at center. Things are looking bright.

But it may take Horford a little longer to shake off last season.

“It was hard because of the inconsistency from our group,” he said of the club that swept Indiana in the first round and won handily in Milwaukee to start the next series — then dropped the next four. “But also I just feel like we had so much talent, just a lot of talent, and we all wanted to do great things. There were just too many of us almost. I just feel like we had so much that it was very, very difficult to essentially keep everybody feeling good and focused on where we wanted to get to. And I do believe that that just kept getting in our way.”

Now he and the Celtics are in each other’s way. The C’s and Sixers will open the season Oct. 23 across the river in Philadelphia and never be far from mind.

And things will get even more interesting for Horford when he makes his first Boston appearance as a 76er on Dec. 12. And, yes, he’s pondered the reception.

“I understand the meaning of this rivalry and obviously of me leaving and the disappointment, so I respect it,” Horford said. “I understand if people are not happy.

“Here’s my thing that I’ll say to you: I won’t hold it against anybody if they feel negatively toward me for leaving. They’ve always known how I feel about them, and I know to a certain extent I was appreciated by a lot of people there.

“I felt like I really gave everything I had. I gave everything I had — on the floor, trying to be the best leader that I could, trying to help the guys as much as I could, putting in the extra work. So no regrets, but disappointment. I understand if people are disappointed. I’m disappointed, too. We didn’t win a championship; we didn’t get to that stage.”

From where Al Horford stood in June amid the still smoldering wreckage of unfulfilled Celtic potential, he could see that stage more clearly farther south down I-95. It’s how he found his way to Camden.