There’s not really any need to wonder, there have been dozens of posts on here speculating about it.
And one of them confirming as an information (fact)
Sad, but true.
Believe me, everyone who are 'speculating' (including myself) really desires that MK's health/playing issues were fake.
Today on Guy's forum, he mentioned that Mark took some hi octane painkillers during the DTRW tour.