"You’ve picked your fly, read the river, and figured out exactly where to drop that fly. You then make a cast to the spot you've chosen, but here’s the kicker: You might be only halfway there, because presentation is half of the entire game. How your fly looks to trout in the few seconds after it hits the water is as important, if not more important, than all the things you did to choose the pattern, figure out where to put it, and then get it there. At the end of the day, fly fishing is all about presentation. So remember this golden rule: You will never beat a large, wise trout into submission."
http://www.fieldandstream.com/blogs/flytalk/the-golden-rule-of-choosing-the-right-fly
The author is absolutely right - Presentation is the name of the game. However he goes on to say, after you've made a good cast with no results, change your fly.
From my perspective, it makes much more sense to change your presentation. If dead drift doesn't work, skate it, swing it, twitch it, sink it, dap it. It makes no sense to me to go to the trouble of changing your fly, then presenting it using exactly the same presentation that didn't work a minute ago.
It seems to me, you can make your fly look like it's alive, or act like it's alive. Best of all worlds - both.
