Nothing new to add, but yeah, Ballard's duck and run is what got him hurt. Martin didn't change direction or body position at all.
I disagree with the last statement, You can see Martin adjust to make sure he hits Ballard, but it's not his fault that Ballard turned in a way that made a shoulder to shoulder hit, into a forearm/shoulder to head hit.
The only thing that you might fault Martin on is when Ballard shifts, so does Martin. Based on the angle of the video @ 2:46 it looks like when Ballard turned Martin was going to miss most of the hit, but then Martin shifts as well to make sure he hits him.