The court heard Ackerman had bruising to his chest but Dr Samarasinghe said force to a person's trunk did not usually cause such a severe brain injury.
There were no notable injuries to Ackerman's head or face other than a bruise to his right temple. Sideline doctor Christian Ibraheem testified he saw Ackerman's head move in a whiplash motion from the tackle but was too far away to determine the point of contact.
Dr Ibraheem said he immediately knew Ackerman had suffered some degree of head injury just from his "gurgling" breathing.
"It could have happened in a car accident," Dr Ibraheem said.
Three of Ackerman's teammates told the court yesterday that they saw Molo hit Ackerman "square in the chin" with a shoulder charge.
Ryan Hansen said he then saw Molo shove and knee Ackerman as he lay injured on the ground to celebrate his tackle.
"Something like that never leaves you," Hansen said. Molo is due to testify at the inquest tomorrow morning.
- AAP