With the loss, 'The Notorious' has now lost two straight fights - both to Poirier - for the first time in his professional MMA career and is 1-3 over his past four appearances.
The pre-fight build-up was marred by ugly scenes, with McGregor claiming he was "gonna make this man pay with his life."
Like many, Poirier was left visibly outraged by McGregor's comments, and took great delight in mocking the former UFC lightweight champion after the fight.
Asked if he felt McGregor has lost his touch, Brown replied via MMA Fighting: “I’m not sure what it is but he did see [sic] much sharper with his tongue in the past.
"Maybe he’s in a tough spot, I don’t know what it is but it also appears he has no lines anymore.
"Where he used to have some lines, some are ethnical but more lines. But those seem to have gone away.
“He doesn’t seem to be quite the same fighter both in the ring and with his promotion wise, too.
"Not sure what it is but something seems different.”
Brown also had words for McGregor's coach John Kavanagh - who had suggested the Irish superstar was 'well on track' to 'getting a finish' against his American rival - suggesting the SBG Ireland supremo was talking utter rubbish.
“It’s not just somebody’s opinion, we’re talking about the judges’ scorecards," he said.
“We had two of the judges had a 10-8 round. So I don’t know how anyone would consider that going well.”
Brown also believes the Louisiana native should be next in line to fight Charles Oliveira for the UFC lightweight title in his next fight after beating McGregor in their trilogy bout.
The 45-year-old added: “At this point, I imagine Oliveira will be next. And who knows what the landscape looks like at the time [McGregor returns].”News Now - Sport News