Honestly, his style is bad in general and I don't think he could improve it without a major overhaul.
And yet, there have been other artists who have managed to do exactly that. Yes, it takes lots of work, and no, there's no guarantee of success, but Rob has never even TRIED to improve, as evidenced by HIS OWN ADMISSION that a lot of his delays can be accounted for by spending too much time playing video games.
In any other profession, anyone who behaved like this would be FIRED, and RIGHTLY SO.