In its submissions to the commission, the FA said: “It is concerning that the club have been unable to improve its control over players and staff following the previous five breaches this season.
“Plainly, reminders from various sources as to the expected standards of behaviour have proven insufficient to affect change in the participants’ behaviour.
“The club must demonstrate a robust response to addressing the incredibly poor period of behaviour by its participants.”
Blades manager Chris Wilder confronted Plymouth players Mustapha Bundu and Darko Gyabi near the away fans following the win which dented United’s automatic promotion hopes.
Having started on the field of play, the incident continued into the tunnel area before security staff helped return order.
The commission was particularly critical of the actions of Wilder, who had debriefed his players on the field before being “overly aggressive” towards Gyabi and Bundu and going on to be “aggressive in the tunnel”.
“The commission also considered a significant aggravating feature was Mr Wilder’s conduct, which the commission considers was provocative and a contributory cause of the mass confrontation,” the report stated.
