It's the man we least suspect...
You see, The Undertaker, much like Mick Foley, has split personalities. During one of his many episodes as Biker Taker, he took a concoction that would keep him in B.T. mode forever. He knew the risks, one of which was that he would be put into a coma for a few months.
The end is nearing, though, and people are gonna pay as the Dead Man rolls out.