The AFL commentator and five-time Hawthorn premiership hero has joined the Saints in a part-time coaching role.

His job will be to school their young forwards, especially King, in the art of forward craft.

St Kilda recruited King with the No.4 pick in last year's national draft and Brereton has seen a lot of him in junior football.

King is making solid progress as he returns from a knee reconstruction and trained on Thursday morning, where Brereton worked with the Saints for the first time.

"He's a huge gold nugget with just a few edges that need knocking off at the moment," Brereton said.

"But he's going to be a player in the league of considerable note."

Brereton said within 20 minutes of watching King at training, he could see areas of improvement.

He noted King's next big challenge will be playing against grown men.

"The world has been full of super talents, though, who haven't gone on," Brereton cautioned.

Brereton is also enthusiastic about the Saints, who have made a surprise 3-1 start to the season.

Despite St Kilda kicking no more than 85 points in a game so far this season, Brereton said their attack boasts plenty of potential.

"It has the makings of being a team that can consistently kick 15-plus (goals) a week," he said.

Brereton has an impressive CV of specialist coaching roles that includes Sav Rocca, Jonathan Brown and Jeremy Cameron.

He had a baptism of fire of Thursday, with an elbow to the face from Matt Parker during a drill.

"I've got a hard head," Brereton said.

His former teammate at Collingwood and Saints coach Alan Richardson said he also learned a lesson during Brereton's first day.

Invited to speak to the team before training, Brereton's couple of minutes extended to half an hour.

Told of Richardson's comments, Brereton didn't break stride with his comeback.

"That is true because Richo said to me before ... 'Can you say a few good things about me as a player?'' Brereton said with a grin.

"So I stood there dumbounded for 15 minutes, trying to remember something Richo had actually done of any note ... no."

Brereton is the latest addition to the new-look Saints coaching group that also features rugby league great Billy Slater in a leadership and development role.

Australian Associated Press