Lutz is a power-hungry politically motivated asshat, and only made Chief because he commands like a dictator. His incompetence leans from the inability to use his mind to solve cases and dig a little deeper into these tricky ones. He only sees what he wants to see, nothing more, nothing less. That's not a detective. That's a closed mind. Because of this weakness and his lack of intelligence, he replaces it with anger issues, a sign of insecurities, and acts like a bully, thinking that will receive him a lot of respect from his officers. Unfortunately, it is also results in him showing that no one else can possibly do their jobs either because he won't work with them one officer to another.

I don't know why he was so mean to them. Maybe he expected more from them so he yells at them or something.