NORTH Melbourne's Ben Jacobs has earned a contract extension for 2016 after reinventing himself as a run-with midfielder this season.

Jacobs signed a one-year deal when his initial two-year contract at North expired at the end of last season, but is believed to have recently activated a trigger clause guaranteeing him a spot on the Roos' list for next season.

The former Port Adelaide player looked to have found his niche in defence in the second half of last season, playing 11 of North's last 12 games, including two of its three finals.

Jacobs remained in defence at the start of this season but was dropped twice in the first eight rounds. Then in the round 11 clash with the Sydney Swans, he was handed a new role, starting as a run-with midfielder on star on-baller Dan Hannebery.

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After keeping Hannebery to 22 possessions and little of his usual influence, Jacobs has since held his own against midfield stars such as Dylan Shiel, Joel Selwood, Dyson Heppell, Tom Rockliff and Marc Murphy.

North senior assistant coach Darren Crocker recently told NMFC.com.au that Jacob's new role had come about through necessity.

"We'd lost 'Wellsy' (Daniel Wells), we'd lost 'Dal' (Nick Dal Santo) for that period and we didn't have Andrew Swallow just before that time because of his broken thumb," Crocker said.

"So we thought, 'Well, let's bring him into the midfield but still have him with that narrow focus of really having a strong defensive mindset', and that's why we got him to start doing some run-with roles on what we consider to be the opposition's more dangerous midfielder."

Jacobs' success in his new role looks to have cemented him a spot in North's team for the first time since he crossed from Port Adelaide at the end of 2012 via pick No.37 in the national draft.

After playing 26 games in two seasons with the Power, Jacobs, the No.16 pick in the 2010 draft, managed just seven games in his first season at North before doubling that tally last season.

As encouraging as his late-season form across half-back was in the latter half of 2014, he was still dropped for the semi-final against Geelong to make way for Brent Harvey's return from suspension.

But the 23-year-old has already played a career-high 15 games this season and, if the Roos qualify for this year's finals series, it's hard to see him being dropped again given how effective he's become as a tagger.

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Crocker said Jacobs' experience in defence gave the Roos confidence that he could match his opponent all over the ground.

"The beauty of his role is that he can now go into the midfield with a narrow focus on an opponent and if that opponent tries to go to a wing, we're comfortable for him to go to a wing," Crocker said.

"And because he's had that experience of playing down back, if that opponent wants to go and play forward, we've got the flexibility of sending Jacobs all the way with him and he's been able to adjust around that.

"He realises now if he sticks to his task and he executes it really well, it shows everyone else how much he's invested in the team's performance and the team's success."