Brennan Cox says he was "lucky to play a good game" when he and Adam Cerra led a youth-laden Fremantle to a rousing win over Adelaide midway through last season.

But the 194cm forward's breakout performance was no fluke. It was the culmination of an uptick in professionalism and understanding what it takes to succeed in the cutthroat AFL.

Cox slotted four-straight majors against the Crows, earning the strong-marking 20-year-old the round 12 NAB AFL Rising Star nomination and coach Ross Lyon's praise for his work "shaving off" rough edges in his game and improving his diet.

While he is only in the early days of his career and far from the finished article, Cox agreed he is coming to grips with life at the elite level and how seemingly minor things like food choices can have a big impact on his football.

"I've had a bit of a problem with 'skinnies' - my skinfolds seem to stay a bit higher than everyone else," Cox told AFL.com.au.

"But (it's) just making the hard choices and cutting out carbs sometimes when I don't need them, or sugar or whatever it is, just to keep those skinnies down, which I did for most of the year. 

"(In the AFL) you go from being a kid eating, drinking whatever you want really, training whenever you want.

"You soon find out quickly what you have to do, what you have to eat and it is a bit of a shock, but you adjust pretty quickly."

Stepping up to League ranks hasn't been entirely smooth sailing for Cox since he was drafted via pick 41 in 2016.

Despite showing his obvious potential with 22 goals in 26 games, the under-18s defender has had to learn forward craft and hone his wayward goalkicking on the big stage, all while still finding his feet at Freo and without much aerial support around him inside 50.

There was also an off-field misdemeanour in his debut season, when Cox and defender Luke Ryan were suspended by the club for drinking alcohol on a six-day break after a Western Derby loss.

But the episode's silver lining was that it rammed home expected standards to Cox and Ryan. 

"It definitely did. Me and Luke, we live together now, and we definitely learned from that mistake and we'd never ever do it again," Cox said.

"After that, we really knew what we were into in the AFL and then we just learned from it and grew from there.

"The leaders got us in and talked to us about it and I went and saw Ross and he was pretty cool.

"They always say 'challenge the behaviour, support the person'. They were pretty good with it.

"The one-match ban sucked, but you learn from it and hopefully improve from it."

Now into his third pre-season, Cox wants to help guide Freo's latest batch of draftees on the right path when they arrive later this month.

On a personal level, he wants to become fitter and stronger this summer, and get on the same page with boom recruits Jesse Hogan and Rory Lobb, plus Matt Taberner, as the tall quartet attempt to fit into the same attack.

"If we get out on the field and train all together and really jell as a group, I think it should be all right," Cox said.

Hogan is currently on restricted duties and still some time away from resuming main training, but he has been sighted at Cockburn undergoing rehab for the navicular problem in his right foot. 

Meanwhile, Lobb has been bonding with some of his new teammates away from footy since his return to Perth.  

"Rory came over to our house with Griffin Logue, because they're living together, and we went and did some go-karting," Cox said.

"He's a great bloke, (but) his go-karting skills need to be a bit more improved.

"I've spoken to Jesse, he's been out here heaps walking laps obviously with his foot.

"He's taking it step by step. I haven't really talked to him about the foot all that much, but he seems to be loving it over here already."