Day has suffered more bone stress in his navicular, ending the midfielder's AFL season.
With Josh Weddle already sidelined for the rest of 2025, Day's latest foot problem is a fresh blow for the Hawks as they battle to stay in the top eight.
They face a massive test on Thursday night against Collingwood, who similarly need a win after dropping three of their last four games.
While navicular injuries can be notoriously tough to heal and have ended AFL careers, Mitchell is upbeat about Day overcoming his foot problem.
He noted Hogan has overcome navicular injuries to star at GWS.
"I'm 100 per cent confident that he'll be back and back consistently," Mitchell said of Day.
"He's a pro and our medical team will work really hard ... Jesse Hogan's had some similar stuff in his career and he's obviously put together a pretty good few years."
Mitchell added Day is coping well with this latest setback. He managed only six senior games this season.
"He's not too bad, he'll be on the bench for us tomorrow night, so he's in a pretty good head space," Mitchell said.
"His navicular site, where he had the surgery, looks pretty good. He has some bone stress in some other parts of his foot - it obviously changed the mechanics of his running.
"It's an issue for us, trying to get him back out and ready for the season ... but he's not back to square one.
"He's still a fair way through his process of getting back."
While Hawthorn are coming off a loss to Adelaide, Mitchell said they are making progress as they try to match it with other top-eight heavyweights.
"We want to put ourselves into a position where we play big games against big clubs and we play in a style that can compete and win those games," he said.
"Now, can we compete in those games? Absolutely. Everyone watched our game against Adelaide last week and said that's two pretty good teams going at it.
"You don't throw the baby out with the bath water and say we're not good enough. We need to refine a couple of things in our game and handle those moments.
"You look at Collingwood's last month - it's pretty easy to say they've lost three out of four, but they've played pretty good footy. Both teams are in pretty good form without getting the points."
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