It is sad his career seems pretty much ended by illness. He could definitely be in the top 5 today if he were still playing IMO. I am not a fan of his playing style so much but he was always fun to have around as he could take out any of the top guys at a given time. He could have made another slam final and won another Masters, and maybe with a bit of luck won a slam before he retired, but it seems that wont ever happen now. His last half year on tour was pretty good too, didnt he win 4 or 5 small tournaments?
Yes, in the last tournament (Bastad 2011) he played, he absolutely destroyed Berdych in the SF and Ferrer in the final in a completely dominant performance. If he never comes back, it was a good way to go out.