The rules says that you must stand on one foot and jump up and down three times, switch feet and jump up and down three times before putting the other foot on the ground. If you jump up and down twice or four times, the rule is broken. If you don't change feet the rule is broken. The rule is the rule and you must follow the rule.
In the case of the Steeler player making a catch, he broke the rule by allowing the ball to become out of his control when it hit the ground. In the heat of the moment the player made a serious misjudgement. Instead of pulling the ball to his body and rolling into the end zone, he extended the ball and exposed it to a possible error, which occurred. Knowing and understand situations is critical in professional football. It's becoming necessary to know what rules may effect you and your position and practice what to do in those situations.