I think what is happening here is the same thing that happened with Boardwalk Empire where the main character isn't bad, it's just that the supporting characters are just so damn entertaining. Mike, Gus, & Hector are killing it much like Capone, Luciano, Chalky, Mueller and the rest of the mob guys were in BE. Nucky & Jimmy right now are kinda like the straight man and these other characters are dropping the punchlines. I still enjoy Jimmy's story but it can't be denied the more entertaining stuff is happening elsewhere on the show.