It turns out that Falcons linebacker Sean Weatherspoon’s hard tackle of Robert Griffin III last season started an injury-related decline that led to Redskins coach Mike Shanahan shutting down the quarterback this week … just in time for the Falcons.

Redskins coach Mike Shanahan said Wednesday that Griffin won’t play again this season because he wants to protect him from the increasing number of hits he’s taking. Second-year quarterback Kirk Cousins will start against the Falcons on Sunday at the Georgia Dome.

Last season, Weatherspoon hit Griffin near the sideline and forced him out of the game with a concussion in the second half of Atlanta’s 24-17 victory at Washington in Week 5.

“It was just a good hit,” Weatherspoon said. “Unfortunately, it rattled him a little bit and things haven’t been the same for him.”

Griffin’s concussion didn’t cause him to miss another game and he went on to become the NFL’s rookie of the year. But it was the first case when Griffin’s tendency to leave the pocket, plus a reluctance to slide before contact, led to injury.

Griffin suffered a right knee injury late in the season and aggravated it during a playoff game against Seattle. Griffin stayed in the game and was ineffective while limping heavily. He had subsequent surgery to repair two torn ligaments in the knee on Jan. 8.

Shanahan said he regrets not taking Griffin out of the Seahawks game because leaving him “not only hurt Robert, but it hurt the team.”

Shanahan said benching Griffin now insures that he will be able to participate in the offseason program and work toward getting healthy for the start of next season. Griffin missed the team’s entire offseason program and didn’t play in any of the four exhibition games. He started against the Eagles in the season opener and was still noticeably favoring the knee.

“Is it worth the risk for three games to play Robert or is it smarter to say, ‘Kirk, you take over?’” Shanahan asked rhetorically.

Shanahan’s decision to bench Griffin is being portrayed in Washington as part a power struggle between the coach and team owner Dan Snyder. Griffin and Snyder have a close relationship while Griffin’s relationship with Shanahan reportedly has been strained since his surgery.

Shanahan said he ran the decision to shut down Griffin by Snyder not because he was required to but because he believes the owner should be consulted on a big decision regarding the franchise quarterback.

“Somebody said I’m going with Kirk because I’m trying to get fired,” Shanahan said. “If I’m trying to get fired, I’m not going to call up Dan Snyder and get an opinion on a player when I don’t have to. And if he says ‘No,’ I’m not going to go that way.”