I love the way that they showed us that Buck has mastered the job, he's a great firefighter who can think quickly and creatively on the spot. But the authoritarian, overly critical father figure is still too much for him. He doesn't know how to get past that (I loved that he heard Eddie's voice in his head when he was trying to calm down). It's a microcosm of Buck's entire life. He's a smart, funny, unique individual but instead of being praised for those traits, he's been overlooked and criticized until he acts out. And then the acting out is all anyone remembers.
It made it all the sweeter that Eddie spent the entire episode having complete faith in Buck, in a way that no one else ever has. Anytime Buck came up with a plan, Eddie trusted it immediately. And it's that faith and trust that will get Buck through whatever is to come for him this season. Much like in the final firehouse scene, Eddie will be that little voice in Buck's head reminding him that he's better than the people who don't bother to look closely enough to see his heart.
