I was listening to an interview and Outerage said that they were really practicing this exact situation and had thoroughly discussed it as late as that morning. He also said that he couldn't really see the other boat at all, just a black blur through a small window in the jib.
I think that Barker made an error having to dodge the first mark up the course that cost them a bit of the lead, possibly enough difference that Sweden was able to get close enough to create the penalty situation. If he had waited slightly longer to tack then he would have cleared the mark and not been dodging. These races come down to the smallest of differences, one error leads to another.
Of course, I say this from my arm chair and not at 30-40 knots with my heart hammering.
Eric, thanks for that continued interpretation - I'm still learning how they're using rules here....the history of their amendments is pretty fascinating. http://noticeboard.acracemgt.com/home/racing-rules/rrsac-changes
Kent, they were really stuck with that tack. I don't think they could go any further because of the boundary but I agree that mark seemed to have surprised them and certainly wasn't helpful. Good to know that even the professionals make that mistake ;-)....and also a good indicator about how much of a difference those little mistakes make.