Fletcher Cox may not have a sack yet through three games this season, but the Eagles defensive tackle has endured longer dry spells over his career. He went five games without a sack last season, was shut out for eight straight weeks in 2016, and in 2014 needed all of nine games before he notched his first quarterback takedown.

But the Eagles’ 1-2 start, the overall lack of statistical production from their pass rush, and Cox’s return after foot surgery has many fans in a semi-state of anxiety and questioning whether the perennial All Pro is slipping.

Cox, however, isn’t worried.

“No. 1, I just need to find a way,” he said Tuesday. “I’m in no panic mode. I’m not frustrated about anything. I’m not mad at anyone. I think the only person I can be mad at is myself. People making a big deal out of me not having a sack in three games, but Aaron Donald’s one of my good friends, and he just got his first sack the other night.”

And Donald, generally considered Cox’s lone equal among NFL defensive tackles, led the league in sacks last season. But Donald’s Rams are 3-0 and they’re 14th in sacks per pass play.

The Eagles, meanwhile, are 31st in the NFL. They’ve tallied just two total sacks and only one is from a defensive lineman — injured tackle Tim Jernigan. Sacks can be overrated, but the four-man rush isn’t generating enough pressure and defensive coordinator Jim Schwartz has had to dial up more all-out blitzes.

In Schwartz’s scheme, that isn’t a consistent recipe for success.

“We’re very reliant on the four-man pass rush,” Schwartz said. “You saw like we’ve made some plays blitzing, we’ve also given up some plays blitzing, and when your rush is getting there without having to blitz, it puts you in a much better position defensively.”

The Eagles have invested heavily in their defensive line, but no more than with Cox. He is the linchpin. But for various reasons — blocking schemes, personnel, injuries to Malik Jackson and Jernigan and his own health — Cox hasn’t been as productive. Eagles coach Doug Pederson and Schwartz have pointed to his recovery and the lack of repetitions in training camp.

“You see a bunch of plays when you see me burst. I feel good,” Cox said. “People may say this or that, but I feel like Fletcher Cox.”

But Cox isn’t playing as many snaps as normal — 70 percent this season vs. 80 last year — for a reason. And the bar is high for the 28-year-old. Here’s what the film says about Cox’s first three games:

Pass-rush double teams

Cox has long drawn the attention of offensive coordinators in their game plans and offensive linemen in their blocking schemes.

Schwartz: They know he wears No. 91, so it makes it hard to hide him. He’s 6-foot-5 and 320 pounds, so he’s always been a person that gets attention.

But it’s mostly his skill that has coordinators circling his number on the chalkboard and taking their chances with the Eagles’ other linemen in one-on-ones. On this play against the Redskins, Cox (No. 91) got doubled while defensive ends Derek Barnett (No. 96) and Brandon Graham (No. 55) were soloed up. Neither won his matchup and quarterback Case Keenum (No. 8) had over three seconds to throw.

The acquisition of Jackson was supposed to give Cox more one-on-one opportunities. But Jackson’s Lisfranc foot injury in Week 1, followed by Jernigan’s foot injury in Week 2, has depleted the Eagles’ depth at tackle.

Pederson: It’s tough. … Having two big injuries at that spot to keep guys fresh and rotated in there is hard.

Cox still has the strength and ability to beat two blockers, as he did here when he split two Lions offensive linemen.

He forced quarterback Matthew Stafford (No. 9) outside — while probably being held — but the Eagles’ coverage broke down and receiver Marvin Jones Jr. (No. 11) gained an easy 17 yards.

Pass-rush one-on-ones

Cox does see his share of one-on-ones, although it’s often on pass plays when the ball is out quick. In the Detroit game, for instance, he was blocked solo on 14 of 24 rushes. This play was just one example, but guard Graham Glasgow (No. 60) did a solid job on Cox as Stafford got the ball out in 2.8 seconds for a 15-yard gain.

Would a 100-percent Cox normally overpower Glasgow? It’s hard to say. But the Eagles can’t wait until he works himself back into elite shape.

Schwartz: Fletch was coming off a major-injury offseason and not getting time in training camp and preseason games. Somebody else’s challenge might be an injury they sustained in Week 1. Somebody else might be playing a little different position. Everybody has got challenges and it doesn’t change our bottom line, which is find a way to come out with a win.

On this one-on-one, Cox faced off with reserve guard Kenny Wiggins (No. 79). Schwartz zero blitzed, though, and Stafford lofted a perfect pass to Jones in man coverage.

Schwartz: When teams choose to try to really take care of our pass rush, other things need to step up. You saw the quarterback holding the ball a long time on some of those.

Extra attention

Cox saw more than one blocker on 20 of 44 snaps (minus kneel downs) vs. the Lions. On this third and 15, the Eagles were playing a soft zone and contain defense, but Cox was triple-teamed.

Hassan Ridegway and Akeem Spence are currently the second and third tackles, but defensive end Vinny Curry has increasingly rushed from inside to offset the loss of Jackson.

Cox: When Malik and Tim get hurt, I don’t think it helps the situation. But I, obviously, think we have two other good players filling those roles, guys who have played a lot of ball.

Max protection

The Eagles say that they’ve seen more seven-man protections, and chip blocks, but they’ve also zero-blitzed more, which often means that more blockers will stay in. On the Lions’ first play from scrimmage, they kept seven in vs. the Eagles’ five. Cox beat Glasgow and forced Stafford to hitch, but he still completed a 7-yard pass.

Cox: Our biggest challenge is when teams do those types of things — chips, seven-man protects — we have to be relentless about our pass rush. We have to get that clock out of our head, thinking that the football is gone.

Sometimes you just have to tip your cap to the other team. The Falcons’ blocking scheme on this Matt Ryan (No. 2) 34-yard pass to Calvin Ridley (No. 18) was excellent. Graham was chipped, Cox was doubled initially, Barnett was doubled throughout and Jernigan (No. 93) was a smidgen late.

Schwartz: When [offenses] choose to chip … sometimes you’re not going to win on your first move. It’s going to be an effort sack as opposed to something that looks nice and clean and on time.

Lack of sacks

Sacks matter. They’re negative-yard plays. They’re high-percentage turnover plays “because generally the quarterback is in the process of trying to throw a ball and the ball is not very secure,” Schwartz said. Former defensive line coach Jim Washburn used to line the walls of his meeting room with pictures of the quarterbacks the Eagles would face, their faces in the crosshairs.

But as Washburn’s sack numbers showed, they could be hollow if the run defense wasn’t sound or points were easily allowed in the red zone.

Schwartz: Sometimes you can get off track if you judge yourself on statistics. This is a win-loss league, and you win, every one of your statistics was good enough. You lose, it’s not.

This third-down play against the Lions was a good example of the Eagles generating pressure even though Stafford wasn’t sacked. Curry (No. 75) penetrated from inside, Graham got around the outside, and they forced the quarterback to hurry and throw short of his target.

But the Eagles face another tough challenge Thursday when they travel to face the Packers and quarterback Aaron Rodgers.

Cox: We’ll get those [sack] numbers. … There’s no pressure in that [defensive line] room. We know what we’ve got in that room.