The only reason why Novak isn't as popular as Roger or Rafa, is ... well he is just not cool enough.
It has nothing to do with his game, or his personality. He is amazing tennis player, he is super nice to everyone... but he just doesn't look cool
, and there is nothing he can do about it.
How can he compare to these guys really? He can't, he just can't.
Novak is No1 player for 2 years now, and has 5 times less followers on facebook then Roger or Rafa.
And he posts regularly, has live chats with fans. Guy tries really hard! And STILL he can't even compare to Rafas or Rogers popularity.