One of the key presumptions in concluding that the crash site was in the 7th arc was that the aircraft continued on a straight autopilot course.
That presumption is now called into serious question. On the other hand, the debris found to date indicates that the collision with the sea was in uncontrolled flight.
One thing I noticed right away with the ping data is that those pings are consistent with a straight path - but far from perfectly consistent. And, of course, they are also consistent with many other paths.