If I remember correctly he was very ill 2010-11, even loosing his signature beard while in hospital. I think his short absence then affected him as he had lots of momentum with Que demande le peuple?, Olympia afterwards as well as his mid-decade hit albums.
I remeber seeing photos of him at the hospital beardless and frail on the old forum. Made me worried as King Kester was also ill at the time. I won't speak on the specutation that went on as to the causes