If the plot Fragrat posted is giving the position, speed and track of ACX Crystal 5 min. after the more detailed track shown in gCaptian's report: http://gcaptain.com/us-navy-destroyer-collides-container-ship/
then it appears that the ACX Crystal was trying to avoid collision by turning to Stbd. and reducing speed. (The last may be because of the turning)
Bearing in mind that both vessels were heading for the same destination in a heavily trafficked shipping lane, it may be logical to assume that their initial courses were not too different, unless the USS Fitzgerald was "doing her own thing", not following the normal shipping lane.
From the position of damages to both vessels I agree that it appears that the relative angle between the two vessels at time of impact could have been somewhere close to 135 degr. as seen from USS Fitzgerald.
But since we have no way of knowing the original heading, or evasive action taken by USS Fitzgerald, if any, we can only speculate on "who's to blame" in normal COLREG terms.
Do we know where the Fitzgerald originated from? Could they have been crossing the shipping lane and also been turning to avoid collision at time of impact?