Specifically, when the casting announcement was made that Robert Knepper was cast as Simeon, I remember the character description of Simeon described him as "Rush's rival and every bit his equal." And indeed, prior to the season premiering everyone from the writers, director, producers and even the other actors were talking about what a thrill it was watching Robert Carlyle and Robert Knepper filming scenes together, and that they had such "powerful performances" when playing off each other. Then the season premieres and the two of them aren't even in the same scene together until the eighth episode, and the only time they're even on screen at the same time is when Rush shoots Simeon. I sure would like to know what everyone was talking about when they were setting up this awesome dynamic the two of them allegedly had.
Maybe they filmed some additional scenes that got deleted in production. Maybe the writers were planning some stories with the two of them but changed their minds before filming started. Or it was just marketing hype.