if you're in gold, your not just fighting against other decks but also against the massive influx of new decks. Chances are your deck moved down not because of other people's decks being played more, but because new decks coming in push it down.
As for the top 10, the fact that they are in the top 10 means they've probably been played a lot. You just weren't one of the players who played them. And honestly, I would rather avoid them since they are most likely strong decks that would put my win streak in jeopardy.