Bertie, yes indeed.
They had had problems with that stadium before, but the senior officer (Brian Mole) had managed to cobble together a protocol to mitigate the deficiencies of the immediate surroundings of the stadium and the stadium itself. It involved active monitoring of crowd movement in the city towards the stadium by Mole himself for hours, closure of the tunnel that led straight to the pens behind the goal when they were full, and diversion of fans to the left and the right into pens that usually filled slower.
Mole was dismissed by Wright a few weeks before the match, and Duckenfield apparently didn't bother familiarising himself with Mole's protocol or the hands on approach Mole had used, or even the layout of the stadium and surrounding streets.
If you look at coverage, esp the 'Anatomy' documentary iirc, you will see that the pens to the left and right of the scene of the tragedy were relatively sparsely filled.
The exact same game had been played the year before, with no deaths or injuries (but there had been concerns about crushing that were ignored by the FA and Sheffield Wednesday, and it was a close call). Same fans, same point of the season, same interest in the game, same deficient stadium with no safety certificate, same alley funneling the crowd into the stadium, same gate and same tunnel, same number of turnstiles. I think this is a strong argument for police collapse as the reason for the deaths, with FA blithe unconcern for fans' welfare and Sheffield Wednesday's greed as contributing factors.
The stadium was the site of a semi final crush in 1981 too, with injuries reported among the Spurs fans in the west end pens.
It's worth noting that over 700 people were injured in 1989.