Judge Mackintosh said Broderick was a "talented sportsman", had performed well at school and the attack appeared "out of character".
The teen had been a Hawke's Bay junior cricket representative and attended Hastings Boys' High School on a sports scholarship.
The judge added there had been a "developmental block in [Broderick's] brain" and the beating, "probably fuelled by alcohol", was a "brain explosion".
Mr Fairbrother said Mr McVicar had contributed to many changes in the criminal justice system, "probably more than he and others realise".
"Every sentence any judge, including Her Honour Judge Mackintosh, hands down is subject to an appeal as of right by either the prosecution or the defence. Remarkably few of [Judge Mackintosh's] sentences are ever appealed."
He added that both sides in the adversarial system found Judge Mackintosh "regularly gets it right".
Mr McVicar, who said he unashamedly represented the victims, replied: "Russell [Fairbrother] knows better than anyone that it is not an even playing field. The offender has an open slather for an appeal, while the Crown finds it far more difficult."
He said Judge Mackintosh was on the Sensible Sentencing Trust's "judge watch list", comprising 12 judges from New Zealand who in the trust's eyes had made questionable decisions when sentencing offenders.
"We do our homework. If it's a one-off case, then you don't make it to our list. It usually comes from a number of victims who have brought their cases to our attention."
Mr Fairbrother said it was appropriate for public comment to be made about sentences, but the rule of law required the public to have confidence in the justice system and to "refrain from personal criticism of a judge".
"If Mr McVicar is genuinely unhappy with a pattern of sentencing, then he should take that up with the Minister of Justice or Parliament's justice and electoral committee."
He later added the onus remained with the defendant or the Crown to prove a mistake had been made when appealing a sentence.
"It's not for someone who wasn't in court to pass judgment on a judge and their decision."