According to a source, Jimmy Butler hasn’t been thrilled with Derrick Rose’s ‘work ethic’

The Jimmy Butler-Derrick Rose so-called feud needed some clarity.

It was provided Wednesday, as a former member of the Bulls said in a phone interview, “Personally, the two are great. Professionally is where they have a difference of opinion.’’

According to the source, Butler considers Rose a friend, but “doesn’t have a lot of respect for his work ethic.’’ In Butler’s mind, Rose was considered the face of the franchise, and if the face of the franchise wasn’t busting his butt in practice every day, especially last season, what was the message to the rest of the team?

“We all saw this coming,’’ the source said.

The source said that Butler also took note of a Rose comment in the playoffs last season, in which the Bulls point guard was asked if Butler had reached superstar status, and responded, “I think it’s going to take a little minute for Jimmy to get there.’’

That explains Butler coming into this season, beating his chest about a lack of leadership and how he’s the one willing to change that. And it’s been more than just words.

“I’m telling you, the amount of work he puts in … even during two-a-days, he would still come in a third time,’’ coach Fred Hoiberg said of Butler. “I mean the guys is unbelievable how much energy he has. He’s just so dedicated to putting the right things in his body, his training, and he wants to continue to add to his game every year. I take my hat off to him. It’s been fun to see everything he’s been able to do out there on the floor.’’

Butler’s teammates have noticed as well. It was Butler who grabbed Doug McDermott this summer, and brought him to San Diego to work out. And it’s been Butler that’s been getting all the young guys in the gym for extra work.

Butler is basically all in on trying to become the superstar that Rose has never understood how to be.

“I was fortunate enough, I played with a guy you might remember named Kevin Garnett,’’ Hoiberg said. “He was one of the best. Everyone followed because of the amount of time guys like that put in the gym. It’s not an accident that guys like that are superstars. When Michael [Jordan] played here, that was another great example of a guy that just pulled everyone with him. And Jimmy wants that.

“He wants to assume that role with leadership, getting guys with him. He had Doug with him for a couple weeks in San Diego, working out with him, and I think that’s a testament to what he wants to do as far as team goals, when you’ve got a guy that’s one of the best players in the league that also works the hardest.’’

A work ethic that Butler won’t be putting the brakes on anytime soon, even with a new five-year, $95-million contract signed this offseason.

“It’s something I have to do if I want to try and take this team to the next step, the next level,’’ Butler said of taking the lead. “Obviously, the ultimate goal is a championship, but I got to bring something new every year. And I just think that leadership this year is key because I’ve been going so hard in practice.

“Teams, they follow. My teammates follow what I do. If I’m in practice and I put my hands on my knees, I’m [ticked] off, they look at me and, ‘Oh, Jimmy’s doing it, I can do it.’ It’s contagious. It’s a building block, but contract or not, I still have to lead.’’