The answer lies in the fact that the aircraft finished at the end of the runway. One will assume that the original touch down point was on the numbers so it's reasonable to assume that whatever happened took this ammount of time and distance so any theories have to fit into a very specific time period and distance. If it had landed wheels up then would it have slid that distance or if it bounced and attempted a GA could it have finished in this position?
If anyone could calculate the slide distance then the distance from planned touchdown to actual touchdown could be calculated and any of our theories would have to fit within this window.