What happened to Sears Roebuck?

Well, they are dead or dying, I think we all know that.  But what killed Sears?   The Wall St Journal had a longish piece on Sears on Saturday.  It was a collection of comments by eight ex Sears people, some of them pretty high up, remarking on Sears collapse.  Too bad none of them wrote about what went wrong.  They all expressed sorrow but none of them gave a coherent story explaining what happened.  Too bad.  I miss Sears.  I noticed just this morning that the little mini Sears we used to have in Littleton is gone.