It's never only about the ratings. There are lots of factors that go into the renewal decision, many of which we never hear about.
Take the weirdly common notion that foreign ratings "don't count." I'm sure they do, in cases where networks are profiting from those ratings. Why would any business ignore any revenue source? But has anyone seen a good listing of foreign ratings, especially one that comprehensively includes all global markets? I sure can't find one. So it's impossible to guess how much they count.
In this case, Warners and Bad Robot lowered the license fee, and that did the trick. I'm sure the fact that Fringe is warming the Friday night deathslot was a factor. What is Fox going to put in the deathslot instead? And their pilots pickups have been light this year, considering how many shows they've cancelled or are bound to cancel.