I actually think Derek was wrong about what his anchor truly was. I personally think the pain of losing Paige, the only person outside of his family to truly love him for who he is and his first love, that sparked his anger. Her death was caused by his selfish request for her to be turned and, in the end, he's the one who had to kill her so she could avoid a slow agonizing death. This led to Derek feeling an emense amount of guilt, pain, and anger something we only get a glimps of when he roars after her death.
I also believe this because, by the time he met Kate he had more contol than he did before Paige. It may not have been perfect but it was better. If Page had lived I believe love would have been his anchor, as it is for Scott.
Having an anchor isn't something that's new. Many people with anger issues, recovoring drug addicts, trauma victims, ect have anchors they just call it diffrent things. It's perfectly normal for a person to use stong emotions, montras, numbers, steps, activities, memories, people, and anything else they can to keep themselves centered.
Honestly I could be over analizing the whole anchor thing but I am a psych studant so I over analize everythin.