You may be right, but I think he can still improve.
I don't know how much you can change these things so late in a career, but he could work on his BH in particular. He could also work on his attacking game more, I think he makes too little use of his abilities in that field.
There's always room for improvement and maybe you're right and he will improve those things in the couple of years he has remaining on this level! I personally believe his attacking game is near perfect, he has the ability to completely dominate and obliterate the opponents ranked below him, which he even has shown against guys like Del Potro, Berdych and Tsonga. However, it's simply impossible for him to make that work against the top 4, because they won't allow him to. With all his weapons countered by superior opponents, there's not a lot he can do to change that match-up. He can't properly play an all or nothing play style where he just tries to jam every shot in the corner with his eyes closed, because he doesn't possesses that skill set nor will he be able to keep that up for an entire match.