Oracle has been playing catch-up for months. The Kiwis got their boat up on foils and stable long before anyone else. Remember Oracle's first attempts at foiling? They looked like they were doing a wheelie around the course! Both teams are still on a very steep learning curve on those boats, but the Kiwis are a bit further along.
Why they decided to try a "foiling tack" at the bottom mark is a mystery, but the maneuver itself is something they had been practicing previously. Barker said that they had been practicing it too. Apparently they need more practice!
I also wonder what the conversation during the race where one of the crew kept saying "we need more time..." and Spithill responded something to the effect that "we've got to sort this out..." was all about. Clearly they were having some issues.
Clearly the Kiwis are the more polished team, and their boat is superior in most conditions, but it isn't fair to suggest that anybody on Oracle should be fired! At least not until the cup is in Auckland!