Dean Cox has provided an insight into where young guns Isaac Heeney and Callum Mills may be spending the bulk of their game time in season 2018, the duo earmarked for extra minutes in the midfield.

Heeney and Mills, who have kicked off their careers in exceptional fashion at opposite ends of the ground, have already spent time on the ball, in different periods last season (Heeney more than Mills), adding an extra layer to a division boasting Josh Kennedy, Dan Hannebery and Luke Parker.

Speaking to Radio 6PR on Wednesday, the newly-appointed assistant coach said he has liked what he has seen from the duo this pre-season but, given their strengths up forward and down back, he’ll have a tough time stealing them away from their respective lines.

“Isaac Heeney and Callum Mills, for third-to-fourth-year players, they’re pretty special at what they can do and their standing within the playing group and leadership qualities they have,” Cox told hosts Paul Haselby and Karl Langdon for Sportsday WA.

“They’ve been doing work with us (Cox and fellow midfield coach Brett Kirk) at the minute, our line-work they’ve been spending a bit of time in there.

“But Cal has become a really damaging half-back and has shut out some key forwards when we’ve needed him to.

“Heeney’s got great versatility, he can play wing or half forward. He’s kicked four to five goals on numerous occasions which not many young players can do.

“The ability to swing him in midfield and spend time forward will be a valuable asset for us.”

The ultimate decision, however, will land with senior coach John Longmire who Cox said has been a great counterpart to work with and under during his formative months at his new football club.

Cox arrived at Sydney following three seasons as an assistant coach at West Coast, joining Steve Johnson who retired after 293 games with Geelong and GWS at the end of 2016.

Both have bought with them some fresh ideas and different perspectives of which, Cox said, Longmire has embraced fully in a united effort to develop the playing list further.

"(Longmire) has been really good to learn under,” Cox added.

“He’s been in the system for eight seasons as senior coach, and like many coaches, hands a lot of responsibility to his assistants during the pre-season.

“All senior coaches demand so much of the playing group – they expect them to play a certain way and rock up in certain shape – and he doesn’t differ from that.

“He has strong values, beliefs and philosophies on the game that he wants us to pass across, but he also wants us to challenge him on that.

“Myself and Steve have come in from different clubs with different ideas and changed up the structure a bit. We get a bit of an opportunity to have a say and give an insight into the way we perceive Sydney and external opinions of them.

“He’s open to that and forthcoming, saying we need to change, but only subtle ones.”