An NFL head coach was talking earlier this season about Washington Redskins quarterback Robert Griffin III and the difficulty of defending him. Nothing simple about that, and the coach, who had studied Griffin since the offseason, said as much.

Griffin is a dynamic runner, an advanced passer and is ahead of most first-year players at reading defenses and reacting to the game’s speed. He has 1,993 passing yards and 529 yards rushing.

Still, the coach was asked, doesn’t Griffin have a weakness? What is his kryptonite? The coach thought for a moment and then shook his head.

“I wish I had some,” said the coach, who requested that he not be identified in exchange for sharing his scouting report on Griffin.

Nine games into Griffin’s first NFL season, opposing teams are working overtime to find ways to stop one of the league’s most dynamic big-play threats.

“Just hit everybody,” New York Giants defensive lineman Chris Canty said. “If you knock everybody down, you don’t have to worry about anything.”

The truth, though, is that defenses have begun to find more specific ways to limit Griffin, if not neutralize him. After interviews with several coaches and defensive players who have studied Griffin, as well as evaluation of the Redskins’ past two games, it is clear that the most popular and successful methods of stopping Griffin have been to keep him in the pocket and eliminate his ability to break off big runs. Basically, force him to become one-dimensional — and rely on his offensive teammates to make mistakes.

“Sometimes it’s not necessarily to make him make a play, as much as making him make a decision,” the NFL coach said.

In losses to the Pittsburgh Steelers and Carolina Panthers, the Redskins’ final two games before the bye week, Griffin was held to a combined 392 passing yards and 61 rushing yards. Other than a game against Atlanta last month, in which he left in the second half with a concussion, those contests represent his lowest two-game yardage totals.

Coaches have learned the hard way to pay close attention to Griffin. If “you turn your back and you’re running downfield,” the head coach said, “he’s out of the gate, because he’ll see it.”

The adjustments have begun

Griffin saw it more than a month ago. When he broke a 76-yard touchdown run Oct. 14 against the Minnesota Vikings, it was a glimpse of the rookie’s improvisational and big-play capability. But it also served as a case study for opposing coaches and what can go wrong if they don’t adjust to Griffin’s talents. Two Vikings linebackers had pursued Griffin, opening a gap; from there, Griffin simply beat the Vikings’ pursuit angles.

“He just outran them,” Carolina Panthers Coach Ron Rivera said.

In the time since that long run, defenses have begun assigning at least one defensive player to watch Griffin at all times. They also have emphasized that defenders must keep Griffin in front of them, though they admit this is not always easy.

“You’ve got a lot you have to defend,” New York Giants Coach Tom Coughlin said.

Defenses have faced a difficult reality since that Minnesota game: Surrender shorter runs and more first downs, with the understanding that it will reduce how often Griffin celebrates in the end zone. In the Redskins’ past three games, defenses have allowed Griffin to average 5.8 yards per carry, but he has only three runs of at least 10 yards — and none in the past two games.

The Steelers used safeties to limit the open field for Griffin, and Carolina assigned cornerbacks to keep tabs on him in obvious running situations.

“Assignment football,” the NFL coach said. “Somebody has to be accountable to him.”

It’s a simple idea, and one defensive coordinators will likely turn to when they face Washington. Three weeks ago, with Steelers safety Will Allen shadowing Griffin in the second quarter, the quarterback tried to find running room after the pocket collapsed; with Allen in pursuit, Griffin threw the ball out of bounds. A week later, Redskins offensive coordinator Kyle Shanahan called a fourth-down option play against the Panthers near the goal line. The extra cornerbacks stuffed Griffin, and the Redskins turned the ball over on downs.

“This is where I go, this is where I belong, and if you’re not there and he hits it, he’s going to hit it fast,” the head coach said. He added that defensive fundamentals are more important when facing Griffin; a small breakdown could lead to a big play. Steelers Coach Mike Tomlin agreed. “More than anything you have to build defenses that are sound,” he said.

Tomlin, who showed his defense a five-minute package of Griffin’s highlights before facing the Redskins on Oct. 28, added that his team’s base defense includes ways to stop the option. But because offenses run the play so infrequently, preparing for Griffin forces a refresher course.

“We knock the dust off our rules,” Tomlin said.

The most effective way to stop Griffin, though, has been for defenses to focus less on Griffin and instead take away his weapons — or just allow the Redskins to make mistakes. Washington’s receivers dropped 10 passes against the Steelers. Meantime, the Redskins’ offense has been penalized 75 times for 649 yards. Both statistics lead the league.

Griffin is an outstanding passer, but waiting to find open receivers can give defenses an opening. Carolina sacked Griffin four times in the second half two weeks ago without having to blitz. The Panthers dropped seven defenders into zones, covering the receivers, and only the four defensive linemen rushed Griffin. As he waited for a receiver to come free, Griffin simply ran out of time, and Charles Johnson and Greg Hardy took turns escorting the rookie to the turf.

The Redskins, needing a quick score, also were flagged for penalties twice late in the fourth quarter against Carolina, nullifying two would-be touchdowns and burning too much time.

Keeping defenses honest

Shanahan understands that the key to wins is keeping defenders and their coaches off-balance, even when self-inflicted problems sometimes make winning a taller order.

The Redskins’ offensive coordinator has begun using unconventional personnel groups more often. Also, before moving toward a hurry-up approach in the fourth quarter against the Panthers, 61 percent of Shanahan’s pass calls began with a play fake. Many of the plays also used unusual formations and either faked or executed variations of the quarterback option.

“One thing that Kyle has done: For each team, he’s got a different type of wrinkle,” said Rivera, a former NFL linebacker and defensive coordinator. “What happens is, you look at it and go: ‘Okay, different personnel group, different alignment — wait, motion, Okay.’ . . . Now you’ve got to adapt to that. It’s putting a lot of pressure on other teams to prepare.”

As defenses hurry to find ways to slow Griffin, Shanahan is working to keep his quarterback a step ahead. Simplicity has, so far, been the best way to defend Griffin; making things complicated gives Shanahan and Griffin their best chance at foiling those defenses.

The race is on and will continue each week, to see which side has outsmarted the other.

“You watch the different things that other people have done, and some people have had success,” Rivera said. “But the other thing, too, is you’re not going to have success for a long time.”