The 22-year-old suffered a corked calf in last Friday night's 21-point loss to Geelong at the SCG, which Longmire was unsure he'd recover from in time to face the Saints.
But Hannebery did, and knew he would from the word go, recovering enough to not only play but rack up 30 disposals, have five inside 50s, three rebound 50s and four tackles to win best on ground honours in the 16-point win at Westpac Stadium.
"He was probably doubtful to play after last week, to be honest," Longmire said.
"He copped a huge cork on his calf but I saw him the next day after last week's game and he never had any doubt.
"I never really saw him without ice on his calf. Every time I saw him he'd have his foot wrapped up or his leg wrapped up in ice."
Hannebery won the medal from teammate Luke Parker and St Kilda captain Nick Riewoldt, actually tying with Parker when the votes were lodged.
As the medal cannot be tied, proceedings took into account the chairman of the voting panel had deemed Hannebery best on ground and he was subsequently awarded the honour.
Longmire said Hannebery's recovery and acquittal of himself was a "real credit" to the sort of person he was.
"It's just a really good lesson to have a young kid like Dan go about it the way he did, really set himself to not only play in a short week, but to contribute and play so well," he said.
"He's a good player, he plays well, he's a consistent player, he's hard and he works really hard and he's also pretty professional getting himself prepared."
Hannebery said it was an honour to win the medal, which is awarded to the player who embodies the spirit of the Anzacs, but it was even better to play on Anzac Day itself.
"It's a privilege to play footy on Anzac Day; you wouldn't compare footy to war but we understood the significance of the day and the occasion," Hannebery said.
"All the guys respected what it was all about and it was great once again to get the win and to contribute to the team was pleasing."
Meanwhile, Longmire said the Swans had "at times" moved back closer to the type of football they prided themselves on after last week's loss to the Cats.
"It was good to get the 90 tackles and to start doing some of that real hard grunt work, which was important for us," he said.
"To lock the opposition up at certain times was useful when they had the momentum and we were able to then get it back.
"The second and third quarters we kicked 6.10, and if we'd hit the scoreboard a bit more in those two quarters it might have made it easier in the end."
Jennifer Phelan is a reporter for AFL Media. Follow her on Twitter @AFL_JenPhelan.
