My kid used to be a ticket agent at ORD for American. She said with the flights to SJU and Santo Domingo, she was always astonished at how much "stuff" these folks tried to take back with them. This flight filled almost every seat. What was the gross weight of this flight? Could that be a factor?
Most accidents are not caused by one single thing but a combination of several.
Some chain of events or mechanical factors are usually the cause.