Funk-
I think it is a big leap to assume that another book is behind the attack (epecially if the motive is to reduce competition to get players).
In the past, when there were actual hacks into the computers, the most often claim I would hear was Russian programmers. The guys there are pretty much out of reach and have quite a pool of programming talent.
So, before we jump to conclusions, does anyone have ANY evidence that it was another sportbook?
Part of the blackmail may be for Pinnacle to keep quite or risk another attack. However, they should be able to contact WWTS or other books hit and compare notes (voices on phone recordings, ip addresses, etc.)
I'm sure if these guys could be identified, there are a few people in this business that wouldn't mind hopping on a plane to pay them a nice visit.