While another Australian coach Willie Peters was being hailed for orchestrating the most famous night in Rovers' distinguished history with the boilover 30-24 triumph, Maguire was magnanimous and not about to make excuses.
His Broncos had surged back in the final 20 minutes after they'd gone 30-4 down but this time, it was too little too late for the side who'd fought back in three successive matches on their run to their NRL grand final triumph.
"We had the momentum but if you do the hard work at the start, you don't put yourself in that position," sighed Maguire.
"We need to realise that before round one," he added, with his mind already flitting towards the champions' season-opener against Penrith at Suncorp Stadium on March 6.
"As much as we came back at the end there, we can't keep doing that.
"They scored some tries. If you're going to wait until the end of the game, over and over, eventually it'll hurt you.
"We made three errors and they scored three tries; you've got to get the little parts of your game right -- and we didn't."
Maguire had no arguments about the final result -- "Congratulations to Hull KR, they jumped out of the blocks, put pressure on us early and we didn't get with them -- and refused to suggest the Broncos' lack of a warm-up game contributed.
"That's an excuse. We prepared well, we practised hard," he added, after an English side won the World Club Challenge for a third successive time.
It left British rugby league crowing about the shock result, after once again a Super League side had made a nonsense of the odds that suggested it would be little more than a walkover for the NRL champions.
Asked how he felt Hull KR would fare in the NRL, Maguire just shrugged: "Well, they just beat us.
"I don't want to make a comment in too much detail, but they've just beaten us. That tells the story."
The reputation of Rovers' coach Peters, the 46-year-old former Rabbitohs halfback, will only have rocketed with the victory and he'll have jumped to the front of the queue as a potential coach for England at the World Cup.
Rovers' players enjoyed outlasting the Brisbane superstars, with man-of-the-match Jez Litten admitting: "I've been off all week ill, and had been having nightmares about Reece Walsh running at me -- and it all came true tonight.
"Having to defend in the halves is a bit different to the middle, and when you've got someone like him coming out the back - credit to the boys on my outside and in the middle.
"The support has been unreal. We wanted to do the English game proud. We obviously get a lot of stick from the Aussies, so it's good to get one over them."
