Severe criticisms of David Duckenfield’s policing of the 1989 FA Cup semi-final at Hillsborough are not based on hindsight, a former match commander has told his trial for manslaughter.

Douglas Hopkins, a Metropolitan police officer at Arsenal’s Highbury stadium in the late 1980s, gave evidence for the prosecution on Monday that Duckenfield failed to prepare thoroughly and showed a “lack of leadership and poor decision-making” at the match, where 96 people were killed in a crush.

Challenged repeatedly on Tuesday by Benjamin Myers QC, defending, that his opinions were based on hindsight, knowing the match between Liverpool and Nottingham Forest at Sheffield Wednesday’s ground had ended in disaster, Hopkins said: “I am applying the standards of a competent match commander preparing himself for the match.”

He agreed he had become more critical of Duckenfield after the 2014-16 inquests into the 96 deaths, where he had said Duckenfield made an effort to prepare for the semi-final and his lack of experience was the principal issue. Hopkins maintained the more experienced match commander, Ch Supt Brian Mole, should have been retained rather than replaced by Duckenfield, who could have shadowed him, and that that was “a fundamental error” by South Yorkshire police.

“I still believe that Mr Mole should have run that [match] because of Mr Duckenfield’s lack of experience,” Hopkins said. “But during the [coroner, Sir John] Goldring inquests, it became quite apparent that he had not prepared properly.”

On Tuesday, Hopkins told Preston crown court he had not understood until later the failures to which Duckenfield had admitted, because he had given evidence straight after him in March 2015. “It was only when I read it in black and white that I realised the extent of his admissions,” he said.

The jury was last week read Duckenfield’s evidence at the inquests, in which he acknowledged serious failures in his preparations and running of the match, and that his “professional failings led to the deaths of 96 innocent men, women and children, and the injuries to many more”.

Hopkins said that as a reasonably competent match commander, Duckenfield should have been more familiar with the layout of Hillsborough at the Leppings Lane end, where the lethal crush took place in the terrace’s central “pens” 3 and 4.

It was a particular mistake, he said, not to fully introduce himself and brief his officers in the police control box or make contact with Sheffield Wednesday officials, including the secretary, Graham Mackrell, and Doug Lock, the chief steward.

On visits to the ground at two Sheffield Wednesday home matches before the semi-final, Duckenfield “could have taken the opportunity to be the match commander”, at the second one on 5 April 1989, with the experienced superintendent Bernard Murray assisting him, Hopkins said.

At the semi-final, the jury has heard, a severe buildup developed at the Leppings Lane turnstiles. Hopkins said he had always thought Murray gave bad advice to Duckenfield by saying they would get everybody in by 3pm, but added: “I would say that you are the match commander, you make your own decision. You can ask for advice but you don’t have to accept it.”

At 2.52pm, Duckenfield agreed to a request to avert injury and possible death by opening an exit gate, C. Neither Murray nor any officer on the concourse inside the ground thought to close the tunnel leading to the pens, Hopkins agreed. He said the officers in the control room had a view of the terrace pens, which were full, so should have known to close the tunnel.

Referring to Duckenfield’s evidence at the inquests that he had not thought where the incoming people would go because his only thought was to save lives by giving them “some sort of relief and comfort in the concourse”, Hopkins said: “I don’t think any policeman would believe that people getting on to that concourse would stay on that concourse … They wanted to see the match.”

The opening of the gate was, in effect, an evacuation from the dangerous situation at the turnstiles, Hopkins said. Duckenfield had stressed in his pre-match briefing the need to ensure “safe passage” if people were evacuated. “That’s what he was doing here, evacuating, but there was no safe passage,” Hopkins said.

Duckenfield, 74, denies gross negligence manslaughter in relation to 95 of the people killed. Mackrell, 69, has pleaded not guilty to two breaches of safety legislation.

Richard Matthews QC, for the prosecution, said the case against the two defendants is expected to end by Thursday.