Fremantle captain Matthew Pavlich says Hayden Ballantyne will be encouraged to retain his aggression in his new role as a member of the club's leadership group.

Ballantyne's growing status at Fremantle was underlined yesterday when the Dockers added him to a group which has been cut from eight to six members for the 2012 season.

Pavlich will captain the club for a record sixth season.

Aaron Sandilands, David Mundy, Luke McPharlin and Matt de Boer were retained, while Paul Duffield, Garrick Ibbotson and Chris Mayne were omitted.

Ballantyne, 24, who finished the pre-season with an improved physique and running style, said he would use his status to not only help younger players but also to challenge senior ones to improve.

"It means I get to help out the younger players and try to lead them the best way I can, and also to challenge the older players, too, like Pav and Aaron," he said.

Pavlich said the Mandurah firebrand had impressed all with his football progress.

"I guess what we have seen is him come from, in the last three years, a player who had immense talent as a small forward pocket into someone who is an elite trainer, elite preparer and one who holds his other teammates to account, and also one who is really desperate to succeed," he said. "I think all of those things have aligned with the fact that he has got into the leadership group.

"During the last period of last season he was injured and his season was over and he spent quite a bit of time with Jason Weber and our strength and conditioning coaches working on his running technique.

"It was over and above what we would normally expect as AFL athletes. That was the first step.

"He has changed his body shape.

"He turned up as a small forward pocket who could run quickly to someone who is really setting some high standards with the way he is going about his training."

Ballantyne has built a reputation as an on-field antagonist in his 44 games for 66 goals, but Pavlich said he would be advised to control rather than change his naturally aggressive approach.

"The advice the coaching group and his peers in the leadership group will give him is that he should be himself and not really change too much, but there is the responsibility that comes with the leadership group and being perceived by your peers as a leader to remain disciplined and adhere to the game plan where possible," Pavlich said. "I think he needs to express himself as he normally does … but there is a fine line."

Coach Ross Lyon said Ballantyne had done nothing but impress him since his arrival.

"All I've seen Hayden do is consistently train hard session in, session out," he said. "He displays a genuine care and interest for his teammates and the staff at the club.

"He's really keen to make Fremantle successful and he certainly challenges teammates in the right manner for them to improve."

Pavlich, 30, said he was keen to continue as skipper, but did not rule out stepping down at some point in the future if the club wanted to groom a new leader.

"I am really comfortable being captain for the rest of my career, but I am also cognisant of not standing in the way of other candidates and stealing their oxygen, further development and growth," he said.

· Adelaide have reappointed Nathan van Berlo as captain and included 21-year-olds Patrick Dangerfield and Rory Sloane in a five-man leadership group.

Van Berlo, 25, will lead Adelaide for a second year, with on-baller Scott Thompson his vice-captain and defender Ben Rutten deputy vice-captain.