As he returns from offseason knee surgery, quarterback Robert Griffin III will have to protect himself better by learning how to slide at the end of a run and throw the ball away to avoid hits, Redskins coach Mike Shanahan said Wednesday.

“You can’t take shots consistently,” Shanahan said at the annual league meeting in Phoenix.

Shanahan, speaking to reporters at the NFC coaches’ breakfast, reiterated that Griffin is ahead of schedule in his recovery from surgery in January for tears of his right anterior cruciate and lateral collateral ligaments. Shanahan said that Griffin is spending six to eight hours per day on his rehabilitation.

He added that “you’re always optimistic” when he was asked about Griffin’s readiness for the regular season opener in September.

But Shanahan acknowledged he does not know if Griffin will be ready.

“If hard work has anything to do with it, he’ll be ready,” Shanahan said.

Griffin must guard against pushing himself so hard that he suffers a setback, Shanahan said.

The Redskins’ offensive system, which includes option plays and runs by Griffin, helps to keep a quarterback healthy by keeping the defense off balance and slowing the pass rush, Shanahan said. He seemed to dismiss the possibility that the system will be overhauled after Griffin’s injury.

Cornerback Biggers agrees to terms

Washington filled at least one hole in its depleted secondary by agreeing to terms with free agent cornerback E.J. Biggers.

Biggers played three seasons with Tampa Bay. He was selected in the seventh round of the 2009 draft and played under current Redskins defensive backs coach Raheem Morris when Morris was coach for the Bucs.

The Associated Press