CONTRACT discussions are unlikely to begin for exciting Bomber Aaron Francis until further into the season as the emerging defender aims to lock down a spot in Essendon's line-up.

Francis, who was pick No.6 at the 2015 NAB AFL Draft, will come out of contract at the end of this season.

He has had a challenging start to his career, requesting a trade back to South Australia at the end of 2017 and last year taking time away from the club to deal with a mental health issue.

However, Francis' return to Essendon and form in the back end of last season was one of the highlights of the Bombers' campaign and showcased his top-end talent.

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Coach John Worsfold told the club had seen a change in the 21-year-old last season that had led to the best patch of senior football of his career.

"He's a different person now. I don't think we saw the real Aaron Francis until halfway through last year," Worsfold said.

Everyone wanted to help him, but nobody knew what we could do to help him. We think he's gotten to that position where he's a good guy around the club and he's had a good pre-season.

Essendon took a firm stance when, after just two years at the club, Francis asked to be traded back to his home state.

The club didn't receive strong enough offers to move on the intercepting defender, who had starred in his under-18 season to be one of their prized draft selections.

Worsfold said the Bombers were glad to have kept Francis at that time, but had been focused on his well-being.

"Ultimately you're only looking at it for Aaron. Don't keep him here, keep the kid's life stressed and he never plays footy for us or anyone. It's a fine line. You don't want to concede if you think you can get them through," he said.

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"We signed Aaron when he was struggling with a view that that's our job. Let's do the job we have to do to help him.

"He said he barracked for Essendon as a kid, he's living his childhood dream, he was just sad and he didn't know why he wasn't the happiest bloke in Australia. He couldn't work it out."

After playing the final five games of last season, including winning a NAB AFL Rising Star nomination, Francis has enjoyed the most consistent pre-season of his career.

Last week he missed a session with hamstring tightness but was cleared of any trouble and trained on Friday as he sets himself to be a part of Essendon's backline on a permanent basis after playing only 10 games in three seasons.

Worsfold said it didn't concern him when the club would move to extend Francis' stay at Essendon, describing contract discussions as "a game of cat and mouse".

Francis will be one of the club's priority re-signings this season, alongside fellow top-10 pick Darcy Parish and small forward Anthony McDonald-Tipungwuti.