Neale's 186th - and almost certainly final - game for the club was the Lions' extraordinary third straight premiership.
The dual Brownlow Medal winner helped sink his former club Fremantle, whose fans booed him during the parade and in Saturday's grand final.
After Neale left the Dockers at the end of 2018, Brisbane played in eight straight finals series that culminated in the Lions' second three-peat this century.
Neale, who has dealt with the fallout of his public marriage breakdown this year, is expected to sign with Collingwood during the trade period.
"One of the things we hadn't been good at for a long, long time as a footy club, even before I turned up as coach, was contested ball," Fagan said.
"You can't win premierships or finals if you're not good at contested ball.
"He's a contested ball king. He in particular led the way in that department.
"Luke Hodge came along and helped our leadership.
"Lachie Neale came along and set the bar high for contested possession.
"That's the biggest legacy he leaves this club.
"He's had a difficult year, he's had lots of challenges - another one this week - and then he had to put up with the crowd booing him all day today.
"His private life is probably not where he would want it to be and he's copped a lot of flak for that, but through it all he's remained resilient and always turned up and played good footy. We're all incredibly grateful to him for that."
Lions star Zac Bailey, who recently turned his back on a free-agency offer from Adelaide to re-sign with Brisbane, was nothing but complimentary about Neale.
"He's a massive reason why we're able to go from where we were on the ladder to a three-time premiership team," Bailey told AAP.
"He's so tough. I've never played with someone as tough as him.
"I don't think there are any hard feelings ... he's just given so much to the club."
In a post-game on-ground interview, Neale let slip it was his last game with Brisbane.
Speaking in the Lions' rooms later, the 33-year-old said it was "probably" the end with Brisbane, but didn't confirm if he would switch to the Magpies.
"I can't thank the club enough for the last eight years," Neale said.
"It's been the best eight years of my life, and they're an amazing club, and I'm so lucky to have been a part of it."
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