The op back had met up with a stronger db .....the db "missed"the tackle and the DT cleaned up.
That's fits the descriptions above by a few. Anyone can take how they want.
To me it was a bad spot after an assisted tackle by the db and dt. They were just so close together it looks like forward progress wasn't given, but under our code it was.
The back engaged broke the tackle . ..but decided to continue backwards as his strength was weaker even though he was heavier....a split second later the DT got him.
Its funny I once suggested having players "appear" on screen as varying in sizes. It could have helped here as the back was About 7 feet beyond the final spot, but visually the movement looks small compared to the players "scale " of size compared to the yard markers on the field.
Thier shoulder pads are equivalent to my dinning room table and the helmet has the circumference of a large deep dish pizza pan .