They probably gave him lots of money. I saw the same thing happen with Ken Follett's World Without End miniseries. I loved the Pillars of the Earth miniseries even with its faults, but WWE was absolutely dreadful. Partly to blame was going from a premium network production to being a broadcast network production. Not only was it a drop in quality, but they had to contend with space for commercials, and it absolutely butchered the story and intent. I had seen Follett being quoted as being happy with it, and the only reason must have been money. I sometimes wonder how authors feel at seeing their work adapted when so many mistakes are being made, with the reality that they've signed off on them and not having any control on the outcome. I think it would make me sad.