Benjamin Myers is defending 74-year-old Mr Duckenfield at Preston Crown Court and called him an "excellent police officer" who is "taking the blame for others".
Mr Duckenfield, a retired chief superintendent for South Yorkshire Police, is accused of gross negligence manslaughter of the 95 Liverpool fans that died at Hillsborough stadium at the FA Cup semi-final in 1989.
He denies all charges.
In his closing speech to the court, Mr Myers said that stadiums and the sport was plagued by hooliganism in the 70s and 80s and it was a "world away" from the way football is today.
Myers told the jury that "it was obvious now, but not then, of the dangers of putting large numbers of people in confined spaces in pens".
Mr Myers described the charges against Duckenfield as "a breathtakingly unfair prosecution case" and that he is being blamed for the failings of others.
He also said the capacity of the west terrace was over-estimated, which had nothing to do with Mr Duckenfield, and that security had been reduced in comparison to other years.
Mr Myers continued and said Mr Duckenfield "was not experienced as a match commander, with limited experience of Hillsborough and had less than three weeks to prepare for the game after being promoted to the role".
Mr Myers also said there were problems with the police radios used on the day.
Concluding his speech, Mr Myers said of Mr Duckenfield that "someone needs to stand up for him" and that he was "an ageing man, not in the best of health".
"You mustn't judge him with hindsight... the starting point is the stadium was potentially lethal."
The trial has been adjourned until Monday.