But it only made them stronger.
The Patriots won that game, 38-14, and haven't lost since, standing at 13-0 as they prepare to face Mangini and the Jets this Sunday at Gillette Stadium in a highly anticipated rematch/grudge match.
It was hard to imagine at the time - when Belichick was being branded a cheater, held a series of uncomfortable press conferences (one of which he walked out on rather than explain his interpretation of the filming rules), and was fined $500,000 by the NFL - but he's come out the winner in all this.
Instead of having to find a way to motivate his awe-inducing assemblage of talent each week, Belichick has built-in inspiration, courtesy of Mangini and what has become known crassly as Spygate. The result has been a team that is chasing history and doing it with a record-setting romp through the league.
Even if he won't admit it.
"I'm telling you that we're going to approach this game like we approached the last one and the one before that," said Belichick. "That's all I can tell you."
Plus, even though commissioner Roger Goodell also fined the Patriots $250,000 and docked them their first-round draft choice in 2008, New England still will have a top 10 pick courtesy of a trade with the San Francisco 49ers.
"At least we did something positive in their eyes," Jets safety Kerry Rhodes told the New York-area media yesterday. "It is what it is for those guys. I'm sure they're using it in some kind of way for themselves. Anybody would."
Meanwhile, Mangini and the Jets seem to have been enveloped by the fallout from the camera confiscation, starting the season 1-8 and benching starting quarterback Chad Pennington, last year's NFL Comeback Player of the Year, in favor of the untested Kellen Clemens.
Clemens, who has started each of the last five games, is 2-4 as a starter - he filled in for an injured Pennington in Week 2 against Baltimore - and has thrown four touchdown passes and nine interceptions.
While the Patriots can clinch home-field advantage throughout the playoffs with a victory, New York (3-10) is playing for pride.
"We're not happy where we are. We definitely thought we would be in the thick of things right now," said Rhodes. "We're not. We're 3-10. But we're going to come out and try to play them as tough as we can."