And no player epitomises those qualities like James Harmes, whose transformation from "unprofessional" rookie to relentless tagger has mirrored the Demons' re-emergence as an AFL force.

The 22-year-old has been a revelation in the second half of this season, shutting down the opposition's best players while also making an impact offensively.

Harmes' reputation as a larrikin and prankster belies a growing professionalism that he admits took some time to develop, telling the AFL website in 2016 that he had come close to being delisted in his first year as a "naive" 18-year-old.

Demons co-captain Jones couldn't be prouder of Harmes, one of a dozen youngsters who have helped propel the Demons into their first finals campaign since 2006.

"He's a humble kid and he just wants to do the best for the team," Jones told AAP.

"He'll do anything for the team. That challenge that's been set for him to play on some of the opposition's best players, he's taken to it like a duck to water and that's because of his passion for the group and his love for his mates.

"I think he epitomises the spirit and sacrifice amongst the group and the character of the kind of players that are playing in our team."

After shutting down Geelong skipper Joel Selwood last week, Harmes is likely to get the job on Hawthorn star Tom Mitchell in Friday night's semi-final.

Jones is well-placed to reflect on the Demons' 12 years of torment as the only player remaining from their last finals tilt.

But the 30-year-old says he never lost faith that things would eventually get better.

"At one stage you would probably suggest it may have just been a dream because of where we were at," Jones said

"But at some point I always believed that the footy club would find its feet and we'd get the right people in the right positions.

"There was a clear plan in place and all the club's done is stuck to that and continued to look to improve and grow."

Australian Associated Press