I'm less skeptical about the claim Abu Sayyaf and his wife had something to do with Kayla Mueller. The released European hostages have written lengthy accounts of their captivity. They were held at the same place as Kayla Mueller for a while. They also have written about their "North African" captors (not just the British ones.) I also don't doubt that there are Tunisian higher-ups in ISIS. The most recent additions to the designated terrorist lists and U.N. sanctions list confirm this.
As for the treasure trove of information seized, that's happened before, when IS leader and former Saddam official Haji Bakr was killed. The documents didn't lead to the degradation or destruction of ISIS. Der Spiegel obtained a copy of hundreds of pages of the documents and provides a really interesting account (in English). Here's how it describes them:
Until now, much of the information about IS has come from fighters who had defected and data sets from the IS internal administration seized in Baghdad. But none of this offered an explanation for the group's meteoric rise to prominence, before air strikes in the late summer of 2014 put a stop to its triumphal march.
For the first time, the Haji Bakr documents now make it possible to reach conclusions on how the IS leadership is organized and what role former officials in the government of ex-dictator Saddam Hussein play in it. Above all, however, they show how the takeover in northern Syria was planned, making the group's later advances into Iraq possible in the first place.
Interestingly, there was little to nothing about religion in the documents.
What Bakr put on paper, page by page, with carefully outlined boxes for individual responsibilities, was nothing less than a blueprint for a takeover. It was not a manifesto of faith, but a technically precise plan for an "Islamic Intelligence State" -- a caliphate run by an organization that resembled East Germany's notorious Stasi domestic intelligence agency.
While I still suspect the raid was launched to get a bigger fish and they missed, that may just be my cynicism. But even if its purpose was to grab al Sayyaf, I think it was a failure for the simple reason that had they succeeded in capturing (versus killing) an IS member involved in guarding Kayla Mueller, they could have flown him to the U.S. and charged him with a crime, for which he'd never see the light of day, which the world would have applauded. It would have sent a powerful message ISIS is not invincible, and shored up support (at least among the warmongers) that the U.S. mission there is valid. Now all they have is a wife who may or may not be complicit, and whose transfer to the U.S. would be viewed by no one as a blow to IS.
I think what we're getting is spin. Why does the U.S. want us to know al Sayyaf and his wife's nationalities, but not their names? (Again, the new name released today comes from an unnamed official.) Since the guy is dead, and his wife missing, and it happened at a camp housing about 500 ISIS members and their families, IS obviously knows who they are. What's the big secret?