The two-time Pro Bowler didn’t understand why Chip Kelly sometimes had him running with the threes during practice or why he had to learn the responsibilities of positions he had never played in the past.
Jackson and Kelly had a little sit-down, and the wide receiver seemed satisfied. He’s been a prized pupil ever since, and here we are two weeks into the season with Jackson leading the NFL with 297 receiving yards.
"We see the play, we know the call and using our tempo and using our speed to get up to the line of scrimmage, a lot of times, we catch people off-guard," Jackson said Wednesday.
In Week 1 against the Redskins, the Eagles relied on a run-heavy attack. But the Chargers came at them with a different tactic, moving a safety up and challenging the outside receivers with man coverage. That didn't work too well as Jackson got loose deep time and again, piling up 193 yards on nine receptions.
Once again, the way Kelly used Jackson showed some of the simple intricacies of this offense. Throughout the course of the game, they ran the same play four times and twice got Jackson open for big plays.
Here's a look at the second play of the game. The Eagles are set up in a 3x1 formation with three receivers to the left of Michael Vick and Jackson set up to the right.
The three receivers to the left are going to run a "stick" concept. Chris Brown explains the concept in great detail here and here. What you need to know for our purposes is that it provides a simple read for the quarterback, who should have somewhere to go with the football against most defensive looks.
Riley Cooper runs a fade down the sideline. Jason Avant runs an out. And Brent Celek runs a stick, essentially heading up field, turning around and finding space away from the defender.
But the key for the Eagles on this play Sunday came on the other side of the field. As you can see, Jackson is singled up against cornerback Shareece Wright, who is playing about 8 yards off the line of scrimmage. There is only one deep safety (red circle), who is stationed in the middle of the field.
As we'll find out, Jackson has a couple options here. If the cornerback is playing off, he can run a comeback route. If the corner is pressing, he can take him deep.
Here, you can see Jackson has a huge cushion. Vick hits him, he turns upfield, and it's a 9-yard gain.
After four straight runs, the Eagles ran the exact same play again, but Todd Herremans got bowled over, and Vick took a sack.
In the second quarter, though, they came back with it a third time.
Again, trips to one side, Jackson isolated on the other and one deep safety.
The key here is how Wright is playing Jackson. He's going to press him up at the line of scrimmage, a dangerous proposition with no safety to that side of the field. Vick knows he has a chance for a shot play. He takes the snap and looks to the three receivers on the left to freeze the safety.
You can see Vick's entire body is turned to the left side of the field.
"He does a great job of looking safeties off," Jackson said. "He doesn't stare me down the whole time. He knows what reads to make, when to throw it and when not to throw it. A lot of times, single-high safety is just staring down and looking at the quarterback, so by moving your eyes, looking the other way and then come back down the field, definitely that 10th of a second keeps safeties off me."
The safety is nowhere near the play as Jackson beats Wright down the sideline.
And when the ball lands in Jackson's hands, the safety's not even outside the numbers yet.
Unfortunately for the Eagles, Jackson could not keep both feet in bounds.
"We were too close to the sideline," Kelly said. "The ball was a little bit too far outside; probably need to leave us a little bit better space."
If Vick's pass is farther away from the sideline, Jackson can go get it and scamper into the end zone for a 69-yard touchdown because there's no other defender to that side of the field. He certainly had a chance to make the play and keep his feet in bounds, but the result was an incompletion. And a costly one at that, as the Eagles were forced to punt five plays later.
Still, though, the concept was sound.
"Shareece Wright was actually following me throughout the whole game," Jackson said afterwards. "He played at [U]SC and I played against him before, and I just felt I was going to be able to take advantage of that matchup. Any time we had a matchup where guys were going to try to get in my face and press me the whole game, I like my options on that."
Kelly would dial up the the play one more time (that's four total for those of you counting at home). This time with 4:49 left in the third quarter.
Hopefully this looks familiar by now. Trips to the left, Jackson isolated to the right with a single-high safety. Once again, Wright is up at the line of scrimmage pressing him.
But this time, Jackson gets an inside release. That gives Vick more room to fit the ball in between him and the sideline.
And Vick throws a beauty. The goal is to place the ball where Jackson can make the grab and keep running, while also making it difficult for the safety to get close. The result is a 61-yard touchdown.
Asked why the Chargers didn't adjust when he was beating them deep all game long, Jackson said: "I don't know. Maybe they feel comfortable and confident in their corners. But myself, it's like, 'OK, if they don't want to change, we can just keep going down the field and running wild.'
"As a wide receiver, I just run. Just run as fast as I can. And I know he's gonna throw it as far as he can."
The Eagles ran the same play four times. They ended up with two completions for 70 yards and a TD. With a minor tweak in execution, that could have easily been three completions for 139 yards.
Again, the heavy passing attack was a result of how the Chargers were setting up defensively.
Asked if defenses are going to have to pick their poison between him burning them deep and LeSean McCoy gashing them on the ground, Jackson said: "Hopefully it does. Pick and choose your poison, like you said. Something as an offense we feel great about, either in the run game or the pass game. I think we have a great balance of being able to go out there and take advantage of what the defense does to us. So regardless of if they want to take something from us, we always have another option."
One other factor to consider with Jackson is where he's lining up. Last year, according to Pro Football Focus, Jackson set up in the slot 17.3 percent of the time. This year, that number has jumped up to 28.8 percent. From the slot, he's made five catches on six targets for 85 yards. In all of 2012, Jackson had nine catches from the slot.
"It's just different looks throughout the whole game," Jackson said. "Usually in the past, I've been outside receiver and that's where I've been the whole game. Being able to be in the slot, being able to be motioned, not always be the outside receiver, inside too, it puts stress on linebackers and safeties in order to guard me as well."
A great example is this third-quarter play.
The key here is not just that Jackson is in the slot. It's what happened on the previous play. Jackson lined up outside, ran deep downfield and had a ball bounce off his fingertips. But once the ball hit the ground, he immediately began the 52-yard jog back to the line of scrimmage.
Thirty seconds after the incompletion hit the ground, he was in the slot as the ball was snapped. Just like when the Eagles go with an unbalanced line, this makes the defense have to adjust on the fly and keeps the opponent on its heels.
"I think the offense does a great job of allowing me to really just go out there and be in the right spot, be moved around, just keep defenses off-guard," Jackson explained. "Because a lot of times I come to the line of scrimmage, they don't know where I'm at."
As for this play, we talked about the concept last week. Vick has three options: hand it off to McCoy, throw the screen to Jason Avant or hit Jackson with the pop pass. Last week, the Eagles ran the same play five times, but it was Brent Celek and Zach Ertz in the spot occupied by Jackson here.
Vick reads the linebacker, who inches up, and connects with Jackson for a 6-yard pickup.
In two games, Jackson has 16 catches on 24 targets for 297 yards. He is tied for the league lead with six grabs of 20+ yards and has an NFL-best 14 receptions that have netted first downs or touchdowns.
Suddenly, for both Jackson and Kelly, that little misunderstanding back in June feels like a long time ago.