Well, looking at the track, the Crystal changes direction several times in "no time". The track shows both 90 and 180 degree turns in between two samples. But just as these ships won't stop on a dime, they won't really turn on one either. To judge exactly what happened in a rather short moment of time based on the tracking is propably not doable. Also, turning 90 degrees is, physically, to decelerate to full stop and accelerate to full speed in the respective directions.
Also, when it comes to the angle at which the ships collided, making a judgement based on the damages on the ACX Crystal alone is completely impossible. For the simple reason that the geometry of the Fitzgerald has a great part in what the damages on the Crystal looks like. It could very well have been a crash at an angle less than 90 degrees as well. I'm not saying it was or even that I think it was, but given the damages we see in the photos, one or the other is not a given. It is important to notice that the Crystal hit the Fitz in the front part of its superstructure. Assuming the Crystal hit the Fitz at exactly 90 degrees, there would still not be any damages to the startboard side of the Crystal, and if the centerine of the bow of the Crystal hit just in front of the Fitz superstructure, we could expect damages looking like what we see. If the Crystal hit Fitz at 135 degrees, perhaps it could look the same, but my guess is that the damages would be much further extended along the sides of both ships, and I think the damages on the Fitz would have been different had she been hit from "behind" at 135 degrees. It would also mean that the Crystal was running at higher speed than the Fitz. But then again, my guess is that the Fitz was stationary, not making way.
If the Crystal did not reverse away from the Fitz, it would mean that the ships have had to come apart while traveling forward, maybe one of them standing still. Which in turn means that both ships must have come to a position where they were alongside of each other. Doing that in a crash like this, without any damage along the side of any of the ships, doesn't sound likely to me. They must, more or less, in that case, have "bounced" off of each other, and that also doesn't sound very likely.
Imagine also all the extra damage inflicted below the waterline, by the bulb, if the crystal didn't "go back" the same way she came in, but instead kept moving forward and sheared away from the Fitz. That's not an argument it didn't happen that way. But it is a darn good reason not to do it that way
I am also thinking that the Crystal had managed to slow down its speed considerably at the time of impact. Had she hit the Fitz the way she did, doing 15 knots, damages to the Fitz would have been way way more serious.
I guess we're having two crews of which neither is all that keen on telling all the details of what happened. I mean, if it takes a couple of days just to agree on whether the crash occurd an hour earlier or later.....