Boardwalk Empire's quality can in many ways be conveyed through the decision to keep Michael Shannon on the show. His character, agent Van Alden, had a storyline that was central to the plot in the shows first two seasons, but was very loosely connected for the third. The show could have easily gotten rid of him and either brought in a new character or spent time on an already present one. It's in this decision that we can see the faults that keeps Boardwalk Empire from becoming an elite show. Instead of seeing that a character has run its course and deciding to let them go, they feel the need to shoehorn them into a story that slowly connects to an important one. They do this not because it creates the most compelling narrative, but because Michael Shannon is an amazing actor and because 'hey, it’s hard to create interesting characters.' This inherent desire by the writers to keep all of its characters while constantly adding new ones isn't a flaw in and of itself, but when not handled deftly it can lead to more exposition and less poignant character moments. Being the show runner of a TV show is kind of like juggling, and in the case of Boardwalk Empire, I feel as if creator Terrence Winter has thrown too many balls in the air.