New details regarding Patrick Dempsey’s exit from Grey’s Anatomy reveal the actor’s behavior contributed to his departure. Since its premiere on ABC in May 2005, Grey’s Anatomy fans have witnessed a number of changes in the cast. One of the most shocking changes occurred in season 11, however, when Dempsey’s Derek Shepherd was killed off.

Introduced in the very first episode of the hospital drama, Derek quickly became known to fans and even casual viewers by the nickname of McDreamy. A surgeon who enters a relationship with the series’ lead character Meredith Grey (Ellen Pompeo), Dempsey appeared as Derek in well over 200 consecutive episodes. So, when his exit from Grey’s Anatomy was announced in 2015, many wondered why the actor was choosing to leave his well-established portrayal behind. At the time, Dempsey explained that he was tired of the rigorous filming schedule and wanted to focus on other projects. But in an upcoming book, two of Grey’s producers shed light on the full story.

Related: Grey’s Anatomy: What Season The Show Turned Bad In

How to Save a Life: The Inside Story of Grey’s Anatomy, by author Lynette Rice, examines the long history of the popular drama. In one chapter, focusing on the importance of Derek’s character and his relationship with Meredith, it’s revealed that Dempsey’s exit from the series was related to HR issues stemming from his behavior on-set. While these issues weren’t sexual in any way, they paint a picture of Dempsey as someone who was growing tired of the ABC show and was a detriment to production overall. Quotes from former executive producers James D. Parriott and Jeannine Renshaw also touch on Demsey’s friction with both Pompeo and series creator Shonda Rhimes. You can read their quotes, via THR, below.

Parriott: “He sort of was terrorizing the set. Some cast members had all sorts of PTSD with him. He had this hold on the set where he knew he could stop production and scare people. The network and studio came down and we had sessions with them. I think he was just done with the show. He didn’t like the inconvenience of coming in every day and working. He and Shonda were at each other’s throats.”

Renshaw: “There were times where Ellen was frustrated with Patrick and she would get angry that he wasn’t working as much. She was very big on having things be fair. She just didn’t like that Patrick would complain that “I’m here too late” or “I’ve been here too long” when she had twice as many scenes in the episode as he did. When I brought it up to Patrick, I would say, “Look around you. These people have been here since six thirty a.m.” He would go, “Oh, yeah.” He would get it. It’s just that actors tend to see things from their own perspective. He’s like a kid. He’s so high energy and would go, “What’s happening next?” He literally goes out of his skin, sitting and waiting. He wants to be out driving his race car or doing something fun. He’s the kid in class who wants to go to recess.”

Derek Shepard and Meredith Grey from Grey's Anatomy

Other quotes in the chapter, from those involved with Grey’s Anatomy at the time, paint Dempsey’s perspective in a slightly more favorable light. They note that he’d long felt frustrated with the drama and Dempsey himself admits that he had thought about leaving along with Sandra Oh years earlier. Regardless, these revelations make clear that the actor’s presence wasn’t helpful and that he was making things difficult for a lot of the crew members. So, regardless of whether the show suffered creatively as a result of Derek’s death, it’s for the best that Dempsey exited when he did.

Dempsey recently reprised the role of Derek in a high-profile guest arc, so it may indicate that previous tensions and disagreements have mellowed. But that’s part of what makes the show so interesting, and so worthy of its own book. In most cases, curious fans would have to wait long after a series has ended to learn the truth about certain story decisions and shocking departures. However, in the case of Grey’s Anatomy, it has beaten the odds and remained on the air for so long that audiences are learning of secrets while new seasons are still airing.

More: Grey’s Anatomy’s Original Romance Plan Explained (Not Meredith & Derek)

Source: THR