“Let your plans be dark and impenetrable as night, and when you move, fall like a thunderbolt.”

-- Sun Tzu, "The Art of War"

FOXBOROUGH, Mass. -- Bill Belichick was in a chipper mood when he arrived at the podium on Wednesday. No, really, he was. He was chatty, self-deprecating and enlightening (if X's and O's are your thing). He was smiling -- well, a couple of times -- and carrying on like a man at the top of his profession, which he is. Just then ...

Can you give us an update on Rob Gronkowski?

In a nanosecond, the sun disappeared and threatening clouds rolled in, turning the New England Patriots' media room into a scene from a Harry Potter movie. Suddenly, it was Voldemort standing in front of the Dunkin' Donuts backdrop, eye-scorching the guy who asked about the health of the All-Pro tight end and dared to challenge Coach Clandestine with a follow-up.

"We'll be compliant with the NFL injury report," said Belichick, sucking the energy out of the room with each word. "When that's required, we'll put it out there."

In that moment, his old nickname -- given to him as a young coach with the New York Giants -- seemed appropriate.

"Doom."

Belichick, whose personal library includes a copy of "The Art of War," will occasionally recite a quote from the ancient Chinese military treatise. When it comes to injuries, Sun Belichick (or Bill Tzu) prefers to keep his plans dark. When he faces the media, he becomes as impenetrable as night.

It's frustrating for reporters, but entertaining for those in the business.

"It's hilarious," former AFC East rival Rex Ryan said of Belichick's no-information news conferences. "He's been doing it that way for years. It's so comical. What are they going to do, fine him? That ain't happening. If other coaches were as vague as he is, they'd probably get fined. But not him."

The Belichick-led Patriots have never been disciplined by the league because of a erroneous injury report. And, by rule, coaches aren't required to comment on injuries, but many elaborate to varying degrees on what appears on the mandatory injury report. Because Belichick speaks to the media at 9 a.m., before practice and before the injury report is released at 4 p.m., he can't comment on what hasn't happened yet -- i.e., which players practiced, which players didn't.

And you wonder why he's known as a genius.

"I'm looking at Bill's facial and body language," one former player said of Belichick's performances for the media, "and you can tell he's thinking, 'Why are these guys wasting my time?'" AP Photo/Steven Senne

What about a courtesy heads-up for reporters? Sorry, the Patriots' minister of information doesn't give out freebies. He also refuses to answer the most basic questions. When a reporter asked last week if Tom Brady -- he of the famously injured right hand -- would be a game-time decision, Belichick paused. For a moment, you thought he might spill something.

No such luck.

"Today is Friday," he droned.

It was Bill being Bill. The man is the most successful coach in NFL history, so it's hard to criticize his methods. But that doesn't mean we can't say he's maddening.

"For me, I'm looking at Bill's facial and body language and you can tell he's thinking, 'Why are these guys wasting my time?'" said Damien Woody, who played on Belichick's first two Super Bowl-winning teams, in 2001 and 2003. "He stonewalls them all. I've seen that movie time and time again, and it's hilarious."

Belichick is like a Buckingham Palace guard when it comes to protecting information -- unflappable and uncompromising. He demands the same of his players. The objective, of course, is to keep the opponent in the dark, lest it gain a competitive advantage. Some believe he also does it to protect his players from further injury.

Whatever the motivation, the message is clear: No yapping to the media about injuries.

"I don't remember him ever dragging a player into his office and saying, 'Look what you said in the Boston Herald,' then fining the player and making him run 10 laps," said Matt Chatham, a member of the Patriots' first three championship teams.

"Then again," he added, "you don't ever want to be in the bad graces. You don't want to raise his ire."

When Brady was interviewed on the winner's stage during the Lamar Hunt Trophy presentation last week after the AFC Championship Game, he was asked by CBS' Jim Nantz about his injured hand. With the world watching, one of the best quarterbacks in history acknowledged, "Coach Belichick doesn't like us talking about injuries too much, but just for you guys here, it was a pretty good cut."

(This from a player who once spent five years on the injury report because of a "shoulder," but never missed a game because of it.)

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Later, at his post-championship news conference, Belichick mocked the perceived magnitude of Brady's hand injury, saying, "We're not talking about open-heart surgery here."

If it were heart surgery, he'd tell reporters to read about it on the injury report.

"That goes back to the Parcells days," Ryan said of Belichick's secretive (some say deceiving) ways.

Bill Parcells and his coaching offspring, including Belichick, seem to have the same approach to injuries. Former New York Jets coach Eric Mangini once told the media that safety Erik Coleman missed training camp because of an "illness." In fact, he underwent an appendectomy and was laid up in the hospital. In 2008, Mangini was fined by the NFL for not disclosing a shoulder injury to quarterback Brett Favre.

Another former Jets coach, Al Groh, once barked at the public relations director in the middle of a news conference because he started to recite the injury report. Groh didn't want reporters to know the information until after the conference, so he could avoid questions.

Parcells was known to try an occasional misdirection play. He was the Dallas Cowboys' coach in 2004 when running back Julius Jones -- listed as "doubtful" after missing seven games with a shoulder injury -- carried the ball 30 times against Ryan's Baltimore Ravens defense.

Gronkowski's concussion will be a storyline during the run-up to Super Bowl LII, but don't expect to hear any illuminating comments from Belichick. He could go Sun Tzu all the way until his final pregame news conference, when he can invoke a familiar line when asked about Gronk's status.

Today is Friday.