Former Patriots quarterback Matt Cassel has a great story about being grilled by Bill Belichick over an opponent's defense

New England Patriots head coach Bill Belichick expects his players to be completely informed about their opponents, and it's a big reason for the team's long-running success,

This is abundantly clear in ESPN's David Fleming's oral history of Belichick's career, in which former players describe how Belichick stressed that they be prepared for everything, knowing the game plan and their opponent inside-out.

Often times, this meant Belichick would spring a pop quiz on them to test their knowledge.

"If he has a motivational style, I'd say that it's constant emotional discomfort," said Rick Venturi, a scout with the Cleveland Browns when Belichick was head coach. "That's why his teams never flatline."

Perhaps the best anecdote comes from former Patriots quarterback Matt Cassel, who recalled being grilled about defensive coverage:

"My rookie year, I got crushed in the back by a corner blitz against the Giants. We're playing them the next year in the last preseason game. [Belichick] asks me, 'OK, Cassel, what front do they like to bring the corner blitz from?' I had looked it up the night before, anticipating it. I said, 'Coach, it's an over.' And he goes, 'Brady?' Well, you know immediately when he goes to the next guy: 'Oh, no. Oh, no.' And Brady says, 'An under.' And he goes, 'Brady's right. I don't want to have to send your mother another note that says, 'Dear Mrs. Cassel, we regret to inform you that your son got killed being a dumbass.'"

Belichick doesn't just ask about defensive coverages, however. Former Patriots cornerback Darius Butler said Belichick would hang quotes around the building and ask players to recall what they said. Former kicker Adam Vinatieri told Fleming, "There were times when he would surprise you and ask you a certain teammate's wife's name."

While it's not unusual for coaches to quiz their players, few do so with the specificity and intensity of Belichick. And as a result, few teams have the long-lasting success the Patriots have enjoyed.

As former running back Marshall Faulk said, "When you know exactly what you're doing and how to do it and why you're doing it, that allows you to play faster, and your talent flows freely. It's like being in class. They hand you a test, you open it up, look at the questions and go, 'Wow, I know all the answers already.'"

Read the entire oral history here>