It's pretty common on GDDR5 graphics cards that memory devices on corners are tilted. It's a somewhat weird tilt on that one chip there in the X, but I doubt it's worth putting too much thoughts on why that is without knowing more of what the H/W engineer(s) doing the layout was thinking. You don't have to match trace lengths (at least within reason, I assume ) with GDDR5, that's why you can squish the memories a lot closer to the ASIC compared to DDR3 used in the original Bone/S.
Yeah, I'm used to seeing corner memory chips angled, but I've never seen this before. They aren't actually angled, they're staggered in distance from the soc, each one changing by a small amount.
Given that you don't have to match trace lengths there has to be a reason, be it power or timings or interference or whatever.
I don't think the render from E3 2016 showed this, so it might be something implemented during the physical implementation of the design (or maybe it was to hide SecSauce ;o ).