I tried finding the phrasing of the quote. I am paraphrasing. I found this one where he mentions his defensive attitude about playing San Francisco in the playoffs.
“I knew Tuesday that they were going to play well," Coach Bill Parcells said today. "When the defense goes in with that attitude, we could lose a game on an individual breakdown, but it's hard to sustain much against us."
He would constantly talk about team efforts winning games and individuals losing them. He wanted to make sure the team knew that they won games together and lost without complete buy in. But he had numerous quotes about one individual can lose a game. This was one. He was a perfectionist, and his message was clear. Lots of easy ways to lose games. He also said he liked QB’s that consistently found ways to get into the end zone. He said if you did not get there, he would not like you.
He would never publicly blame Dak if he was coaching because his job would be to improve Dak’s playoff performance behind closed doors. But he did believe one individual’s mistake could lose a game.