ASHBURN, Va. — For the fifth time in the last 13 games, the Redskins (3-11) have changed their starting quarterback — and it’s not because Robert Griffin III played pretty well Sunday in a loss to the New York Giants.

Jay Gruden put Griffin back in the lineup for Saturday’s game with Philadelphia (9-5) only because the first-year coach’s favored quarterback, Colt McCoy, went on injured reserve after re-injuring his neck against the Giants.

“It’s been a tough deal for all three quarterbacks,” Gruden said. “Robert had the job Week 1, hurt his ankle (in Week 2) and opened the door for Kirk (Cousins, who was benched after starting Weeks 3-7). Then, Colt had a great opportunity. All three of them had great opportunities to take this thing and run with it. Unfortunately, we just haven’t had the stability at that position. Durability is a very important trait at the position. You’ve got to be dependable. Unfortunately, (Griffin has) had a couple fluke injuries. That’s an issue.”

So is protection: The Redskins have surrendered 36 sacks over the last six games.

“We’ve got to do the best we can to keep him upright, get him out of the pocket, run the ball,” Gruden said. “Obviously there’s some worries there that he might get injured, but I think as a play caller, utilizing Robert to the best of our abilities, we can’t worry about the ‘injury-prone’ factor. We have to call the game to best utilize his strengths, and that puts him at risk sometimes.

“Hopefully, he does a good job of protecting his body, slide when he has to slide, get out of bounds when he has to get out of bounds, and throwing the ball away when he can throw the ball away and avoid the hits. That all comes with experience and playing the position.”

Gruden, a star quarterback in the Arena League, acknowledged that Griffin, who won the Heisman Trophy in a shotgun/spread offense at Baylor, hasn’t had much experience as a pocket passer.

“This position is very difficult, especially when you’re learning new concepts with a new system,” Gruden said. “It takes time. So it’s important for us to try and have some success on first and second down so we don’t have to drop back and throw it 30 times a game. But, eventually, when you get behind, you get in third down. … The drop-back reads and progressions have to be accomplished and that’s something we’re fighting through right now.”

Gruden said Griffin, who came into this season trying to prove that his ugly 2013 campaign under former coach Mike Shanahan was a fluke, might have been trying too hard.

“I think he might have been pressing a little too much early in the season, putting a little bit too much pressure on himself,” Gruden said. “(Now he) has a better understanding and a little bit more confidence. I don’t expect perfection from him, but we want to see improvement (on) a weekly basis. We’ve always seen that he can run. The issue is keeping him upright in the pocket, getting the ball out of his hands when he has to … and when it’s his turn to run, elude some people and make some plays.”

Against the Giants, Griffin completed 18 of 27 passes for 236 yards and a touchdown, with a 109.4 passer rating, while rushing five times for 46 yards.

He said he learned from the longest relief stint of his football career.

“You’ve got to go out there when your number is called and be ready to go and play with an enthusiasm and a fire in your belly. And that’s what I did,” Griffin said. “You learn from your mistakes, you see where you could have gotten the ball out in certain situations, and then you apply that to the next game. … I haven’t played very many games this year, so my goal is to always go out there and be the guy.”

Griffin wasn’t the guy when the Redskins pushed the Eagles to the wall before losing 37-34 earlier this season. That was Cousins’ first start, and he ripped Philadelphia’s defense for 427 yards and three touchdowns. So despite the discrepancy in their records, Gruden is optimistic that Washington could end its six-game losing streak on Saturday.

“We had some big plays, (but) unfortunately at the end we had a chance to tie the game or win the game and didn’t get it done,” Gruden said. “(Cousins is) No. 2 right now. He’s got to wait his turn. Hopefully Robert does a good job and we don’t have to worry about it. One thing about Robert: I know he’s going to give it his best shot. As a coach, that’s all you want.”

With just one more game after Saturday’s, at least only one more quarterback change is possible.

SERIES HISTORY: The Redskins lead 80-73-5. The most memorable recent game was in 2010 in Washington, where former Philadelphia quarterback Donovan McNabb and the Redskins were blitzed by the Eagles 59-28 in a much-hyped “Monday Night Football” matchup.

NOTES: QB Colt McCoy (neck) was placed on injured reserve on Dec. 16. OLB Jackson Jeffcoat was promoted from the practice squad to take McCoy’s roster spot. … OT Trent Williams didn’t practice Wednesday after leaving the Giants’ game during the third quarter with a strained right shoulder. Tom Compton moved from right tackle to the left side and Tyler Polumbus resumed his spot, which he lost to Compton at halftime in Week 7. … Also not practicing were DE Jason Hatcher (knee), OLB Gabe Miller (ankle), LB Keenan Robinson (knee) and TE Jordan Reed (birth of child).