Well you also lose win streaks in top 5 - there are no more. You may not even realize it. I'd share some of my lists with you but honestly, I'm sure you know where they all are at this point anyway.
One key thing in the top 3-5, is adjusting to the meta you're seeing. Not daily, not hourly, but game by game. If I hit 3 freeze mages out of 4 games, I switch to Jade Druid. If I hit 2 straight Jade Druids, I switch to Miracle Rogue, etc etc. That's how most legend players get their edge. If you stick to one deck because you're comfortable with it, you could be playing into a meta that it's just not good for. Watch reddit/r/competitiveHS - as soon as someone posts a deck there, it's 60% of ladder. When Token Shaman was posted there 2 months ago, I switched to a control Priest that farmed the ever loving #### out of the Shaman decks and high rolled something like 23-2 from rank 15 to 3, etc etc.