There was no blindsided concerning BP, the "Bean counters" were calling the shots instead of their engineers and service company people.
Most bean counters are too busy complying with federal regulations to get involved with operational minutia.
Do you have the details? I’ve seen the statements that they were using procedures that skimped on safety, but you can always say this. Always! The ideal is never realized, so when the actual meets with failure, the ideal is trotted out as the innocent betrayed. This is myth as failure analysis, and I don’t buy it.
To me, they were just way wide of the mark here; Engineers, bean-counters and all. They got something that they just didn’t expect. Why not? That’s my question.
I think the blowout was caused by clathrate. The phase boundary for methane clathrate is right along the depth and temperature of the well head, so you had clathrate coming up and “evaporating” in a process much like a volcanic eruption. I don’t see why this should have been anything unknown to them, but it looks like they didn’t see it coming.