ASHBURN, Va. — After the Washington Redskins passed for only 106 yards and produced just one touchdown and two field goals in Sunday’s 17-13 loss at San Francisco, coach Jay Gruden didn’t promise on Monday that Robert Griffin III would remain the starting quarterback this Sunday at Indianapolis.

“We have to look at our offense in general, what the reason is for our lack of production the last two games,” said Gruden, whose offense managed just seven points the previous week against Tampa Bay and converted just six of 26 third downs (23 percent) against the Buccaneers and 49ers.

“We’ve been poor on third down and you can’t attribute it all to Robert. He is the quarterback, though, so we have to look at every avenue and figure out where we can improve. … Our starting lineup is not etched in stone for Sunday’s game. We’ll evaluate everybody today and tomorrow. … But we have every intent that Robert will be the starter this week.”

Gruden said that Griffin “made strides” against the 49ers although he passed for 101 fewer yards and was sacked five times in 25 drop-backs compared to going down six times in 38 drop-backs against the Bucs.

“There’s a lot of other things that go into the passing game,” Gruden said. “We’ve got a rookie left tackle playing his first game, we didn’t air it out,” Gruden said, referring to Morgan Moss stepping in for veteran Trent Williams.

“We had positive field position and didn’t want to take a lot of risk down the field. … We had a great opportunity to win the game and we just didn’t do a good enough job in the passing game with our protection when we had to.”

Griffin has been sacked 16 times in the three games since he returned to the lineup as Gruden, who calls the plays, continues to scale back the offense for his struggling quarterback.

“We’ve got some issues,” Gruden said. “We feel like we’ve got the weapons.”

He was, no doubt, referring to receivers DeSean Jackson and Pierre Garcon, who combined for just 10 catches for 114 yards against the Bucs and 49ers.

“To have (only 106) yards passing is unheard of in this day and age with the receivers that we have. … We’ve got to … work on plays that are conducive to getting the ball out quicker. We’re putting too much stress, I think, on third-and-long on our tackles and on our inside people right now, probably too much stress on Robert too. … You’ve got to continue to believe in your progressions and your routes and your footwork, just keep going.”

That’s Griffin’s intent even though he hasn’t won a game in which he has played into the second quarter in more than a year.

“I feel like I have to play better and find ways to make those big plays happen no matter what’s going on,” said the 2012 Offensive Rookie of the Year, who hasn’t been the same dynamic dual-threat quarterback since tearing his right ACL and LCL in a playoff loss to Seattle nearly 23 months ago. “Hats off to our defense, they played extremely well and kept us in the game, the entire game. Their defense came out and played well, hats off to them as well. … No matter how grim it might look or whatever’s being said, we’re going to stay positive. We feel like we can still have some success this year and continue to get better.”

Jackson, who has alternately defended, consoled and seemingly taken a shot at Griffin during the last month, was supportive of the quarterback after another tough day for the passing game.

“We’re in a slump,” said Jackson, who did have a 32-yard catch and run in San Francisco, his 11th reception of at least 30 yards. “We’re all in it together. There’s no one man [responsible]. … Robert did a good job today. He had a lot of pressure on him. With the circumstances given, he did what he could do. He made the best out of it.”

Washington’s defense definitely did that. The unit began without starting nose tackle Chris Baker (clavicle) and starting cornerback David Amerson (inactive after violating a team rule) and lost corners Tracy Porter (shoulder) and E.J. Biggers (concussion) during the game.

“A great performance,” Gruden said about the defense, which did allow the game-winning touchdown drive late, but grabbed three takeaways.

“They could’ve hung their heads (since) the offense wasn’t giving them anything to be excited about but these guys competed their butts off. The front did a great job of neutralizing the running game and then our pass rush was effective.”

Notes: Starting cornerback David Amerson was inactive for violating a team rule. Replacement Tracy Porter went out with a separated shoulder. Nickel back E.J. Biggers was sidelined with a concussion. Greg Ducre, seeing his first NFL action on defense, joined rookie Bashaud Breeland as the regular corners with safeties Brandon Meriweather and Phillip Thomas also seeing time there in certain packages. Still, the Redskins forced three turnovers and held the 49ers to just 17 points and 312 yards. . . .

Special teams captain Adam Hayward suffered a season-ending tibial plateau fracture in his right leg while downing a punt in the third quarter.

REPORT CARD VS. 49ERS

–PASSING OFFENSE: D-minus — Quarterback Robert Griffin III did complete 11 of 19 passes and didn’t throw an interception, but that was about the extent of the positives for Washington’s passing game, which produced just 106 yards while surrendering 29 on five sacks. Griffin, appeared less out of sorts than he was in his much-criticized previous outing against Tampa Bay. However, the passing attack was still of the popgun variety as Griffin rarely threw a ball more than 15 yards. The line didn’t help, particularly at left tackle where rookie Morgan Moses was often manhandled by San Francisco linebacker Aldon Smith before end Justin Smith got him for a sack and strip of Griffin that sealed the verdict.

–RUSHING OFFENSE: A — Despite the lack of a passing game, running back Alfred Morris continued his November surge with 125 yards on 21 carries, including a season-best 30-yard burst. Morris ran hard and the line, particularly right tackle Tom Compton, opened good holes. Fullback Darrel Young was stuffed twice in a row at the goal line before Morris took the ball into the end zone. Griffin took a big hit while running 8 yards to set up one of Kai Forbath’s field goals.

–PASS DEFENSE: B-minus — The good news was that rookie cornerback Greg Ducre recorded an interception in his first NFL game on defense and that outside linebacker Ryan Kerrigan and end Jason Hatcher each surfaced from slumps with sacks. The bad news is that Ducre was forced into action because David Amerson was inactive after breaking a team rule, and Tracy Porter, starting for Amerson, exited with a separated shoulder, and fellow cornerback E.J. Biggers was sidelined with a concussion. Despite all that chaos, the Redskins held their own against the 49ers’ passing game, except for Anquan Boldin, who scored the first touchdown on a 30-yard catch against Meriweather and set up the game-winner with a 24-year grab against rookie cornerback Bashaud Breeland. Rookie outside linebacker Trent Murphy had Washington’s only hurry that wasn’t a sack.

–RUSH DEFENSE: A — Washington couldn’t stop Frank Gore from jump-starting the winning drive on fourth-and-1 from the San Francisco 34 or fellow running back Carlos Hyde from finishing it on first-and-goal from the 4. However, the Redskins still limited the 49ers to just 66 yards on 29 carries. Inside linebackers Keenan Robinson and Perry Riley led the tacklers while nose tackle Barry Cofield anchored the line in his first start in place of the injured Chris Baker since the opener.

–SPECIAL TEAMS: B-minus — Punter Tress Way continued to make his case for the Pro Bowl, averaging 46.6 yards gross and a 45.6 net on eight punts, three of which he placed inside San Francisco’s 10. Kicker Kai Forbath bounced back from two missed field goals the previous Sunday with two successful tries, the second a 46-yarder that gave Washington its only lead, 13-10, with 7:42 remaining..

COACHING: F — Gruden kept his team together despite more woes, some self-inflicted and some not, but the Redskins still lost their third straight game to ensure the 12th non-winning season of Dan Snyder’s 16 as owner. The coach’s play-calling worked for the running game but not the passing game. Defensive coordinator Jim Haslett’s rollercoaster month continued with a strong effort despite such personnel deficiencies that recent practice squad rookie Greg Ducre and safety Brandon Meriweather each saw time at cornerback. And yet Washington produced three takeaways, just six fewer than it had registered in its previous 10 games combined.