I'm just going to give some random thoughts here. This thread is 67 pages long, so forgive me if I'm just repeating the obvious.
As has been mentioned, if Stone are to be believed, Arrogant Bastard is the result of accidentally scaling the pale ale recipe incorrectly, resulting in something much stronger. However, they also say that the happy accident occurred while they were in the process of "triangulating" the pale ale recipe on a home brewing system, which leads me to believe they had not settled on the "perfect" recipe yet and were trying new things on a small scale, which makes me fairly confident in assuming the modern well-known Stone pale ale recipe is not necessarily reflective of Arrogant Bastard's recipe.
The actual basic idea for the pale ale is fairly close to the recipe being brewed here. ~87% pale malt, ~13% crystal 60/75, mashed at 156ºF, bittering charge at 90 minutes, late additions for flavour/aroma, no dry hop.
I think it's safe to assume that Stone pale ale was always mashed fairly high even in those early days, since it was always intended to be a fairly malty beer. I quote, "We wanted to do a pale ale without using Cascade hops, making it more of a hybrid pale ale and adding an American flair to a more English-style recipe."
Maybe they were experimenting with using lesser amounts of stronger crystal malts? I think it's safe to assume that the crystal malt(s) used in Arrogant Bastard are darker than 60/75 lovibond, so it makes sense that they would drop the percentage of crystal.
It also makes sense that it would be a foreign and/or unusual malt like Special B, since they were aiming for a non-conventional style.
The fact that they apparently did not notice the mistake until the brew day was (almost?) finished leads me to believe that they probably didn't mess up the mash temperature, or the boiling time, I think it's fairly safe to assume they are still boiling for 90 minutes and mashing high.
Chinook hops were definitely around in 1995 when Arrogant Bastard first came to be, they were first released in 1985. Originally bred from a Goldings variety, it seems like it would have been a good candidate to try out for their UK/US hybrid pale ale.
Just some thoughts.