Essendon coach John Worsfold says it remains unclear whether veteran midfielder Jobe Watson will play on in 2018. 

Watson, 32, is out of contract at the end of the season and has at times struggled for form in 2017 after he was suspended during 2016 as a result of the Bombers' supplements saga. 

Worsfold has previously said Watson is in Essendon's best team for 2017, but asked on Channel 7's Game Day on Sunday if he was in the club's best 22 for 2018, Worsfold said that would depend on the veteran's body and the development of younger players. 

"There's a lot of factors to take into account," Worsfold said. "There's things like where does Andy McGrath play his best footy? Does he step up and become a midfielder next year? [Darcy] Parish is growing and I expect will be a more dominant force through the midfield next year.

"So looking at that and the balance of the team, who we recruit in this year and how Jobe is feeling. That's obviously the biggest part of it – where's Jobe at physically and mentally? That's the first part, does Jobe want to play on?

"And then where does he fit in our group? So that's a two-way conversation that at this stage there's no urgency because there is still a lot of footy to go. We want to see how Jobe is feeling at the end of the season as opposed to now." 

Watson has played 15 of a possible 17 games for Essendon this year. He was rested for a trip to Perth to play Fremantle in May and missed the match against St Kilda in round 17. He had a solid 23 disposal effort against Collingwood in round 16. 

Worsfold was more sure on the future of another out-of-contract player, David Zaharakis. 

The midfielder has been in sparkling form in the second half of the season and Worsfold was clear that both parties saw a future for the 27-year-old at the Bombers. 

"Yeah absolutely [Zaharakis wants to play next year] and the negotiations are going well," Worsfold said. "I had a chat with our list manager the other day just to get an update and that's tracking along really well so Zaka [Zaharakis] is really excited about the future of Essendon as well and we're pretty confident we'll make our announcement sooner rather than later." 

The Bombers also face decisions on veterans James Kelly and Brent Stanton who are out of contract for 2018. Kelly has been in good form, while Stanton has only played seven games this year, his last in round 11.