What do you mean they have been predictable exactly? Easy to predict who will cover? Line movements have been wrong quite a bit, especially the very Large Laker game 4 one. They might have paid for their whole playoffs on that game alone.
I would imagine books have made money on the Boston and Lakers series, as both teams tend to be very popular. I haven't looked but I think unders have done well and that is usually a good sign for books.