It must be about the action. Big fish are predators. It takes big undulating, shimmering bugs, below and above the surface, to grab the attention of that alpha trout. Without action, there is no reaction, right? So those rubber legs and wiggly wood duck feathers, soft hackles and so forth are the ticket. Then again, you can catch mighty large fish by dead-drifting a lifeless egg in the right place at the right time.