"He's bounced out of his last run really well, he's eaten up and his work has been really good since, so we're really happy with him heading into the Derby on Saturday."
Blake Shinn has been aboard Autumn Mystery in his last two starts that have resulted in victories, but the trainer concedes the wide draw is a concern.
He said he won't be tying Shinn down with any instructions.
"A jockey of Blake's experience, you don't have to give them any instructions," Hunter said.
"He's ridden at that level numerous times and he's got the experience on his side. He's one of the smartest decision makers out there of the jockeys.
"He's been a bargain buy for the owners. I honestly thought on his pedigree he would be a $200,000 or $300,000 horse, a bit outside our price budget.
"He's been fantastic for the owners. He owes them nothing and he's going to take them on a ride.
"Whatever he does on Saturday, in 12 months' time, they've got a lot of fun times in front of them."