We see this at work on the Reds. Drew Stubbs is a talented CF, but he's just sort of average for his position because guys like Carlos Gomez and Michael Bourn also play CF. Excellence in CF is pretty common and it's a bit premature to declare Trout superior to his group of highly qualified peers.
So definitely give Trout points for defense, but I recommend a little reserve in turning it into a gazillion dollar prize. He has a solid defensive advantage. If everything else is equal, then that should put him over the top. I think some analysis on this has been quick to get to everything else is equal.