Depends who the players at the very top are. Only Ronaldo and Messi keep a level of consistency when it comes to performance. Everyone else goes through dips of form.I agree in general, obviously, but then again he is 'out form a bit' for a few months now. Which in my view shouldn't happen to players at the very top. Where he literally belonged for few seasons now.
Lewandowski, who is arguably the best striker in the world, went through a bit a couple seasons ago. Kane hasnt been himself for Spurs. Griezmann, etc. So, as I said, depends what you mean by 'players at the very top'.