POTENTIAL has been a word associated with Jonathon Marsh's career, but he is actively seeking to change that perception and establish himself as a hard-nosed defender in Collingwood's team.

The tag has followed Marsh since he displayed his lightning speed (he ran a 2.78 second 20m sprint at the Combine) and leaping ability in patches as a mobile forward – a position he had not played before – for East Fremantle and Western Australia in 2013.

It hung around when he fell through to Collingwood's pick No.77 after an inconsistent year at under-18 level where he could provide only glimpses of his talent. Instantly Magpie supporters viewed Marsh as a project player who would take time to develop.

"The word potential gets thrown around quite loosely but I actually took offence to it," Marsh told AFL.com.au.

"I wanted to make sure that I wasn't one of those players that just fizzled out."

The turning point for Marsh came after his third VFL game in his first season at Collingwood in 2014. He had just played "another stinker" and was growing frustrated that the Magpies were persisting with him up forward.

Marsh, who stands 194cm, has never seen himself as a forward. Even when he was playing colts football in that position for East Fremantle in 2013, recruiters would ask him: 'Why aren't you marking the footy?' and 'Why aren't you playing your forward role like a forward?'

"I actually went to Craig McRae (then Collingwood development coach) and Dale Tapping (VFL coach) and nearly begged them to throw me into another position," Marsh said.

"Initially we had the conversation about grinding it out and I went away and told myself, 'I can get through this'.

"Then I came into the club later in the week and they said, 'Marshy we're going to chuck you down back'. They listened to me and understood my reasons and we've never really looked back."

Being a defender is more familiar to Marsh. He can see what is in front of him and make decisions on instinct, putting his physical attributes to good use.

"For my development it was the best move and I think if I'd been stuck playing forward my career may have ended sooner rather than later," Marsh said.

Marsh, 20, is set to play his fourth consecutive game, the 11^th of his career, against West Coast at the MCG on Saturday.

The work he put in with older brother Harry, a rookie on the Sydney Swans' list, in the off-season at home in Margaret River, the famous surf spot three hours south of Perth, is starting to pay off and he is rid of the hamstring problems that hampered the early part of his career.

"Having a brother in the AFL is quite a blessing, because not only do we support each other throughout the year, but in the off-season we get to push each other and train together," Marsh said.

Jonathon and Harry were on hand as their grandfather, Ray Sorrell, was inducted into the Australian Football Hall of Fame earlier this year.

Sorrell was a dual Sandover medallist and a smart-moving centreman who played for East Fremantle and South Fremantle.

"It was fantastic to see AFL stars coming up to my granddad and saying that growing up he was one of the reasons why they wanted to become a footballer, which was absolutely surreal," Marsh said.

Marsh plans to end the season for the Magpies on a high note and wants to do his famous grandfather proud throughout his Collingwood career.

"Hopefully I keep developing at a rapid rate, because I am an impatient person," Marsh said.