All was right in the Eagles' world.
And then it appeared as if something had gone terribly wrong.
Maclin, back from a left hamstring injury that kept him out of last week's game against New England, ran a straight-line pattern for 10 yards, then crashed to the ground without being touched as he tried to cut inside of Pittsburgh cornerback Cortez Allen. The replay showed what caused the fall. Maclin's right leg locked awkwardly, and now he was on the ground at midfield rubbing the area just below his knee.
"Obviously, the worst of the worst went through [my] head when Jeremy went down," Cooper said after the Eagles' 31-21 victory. "Immediately I felt so bad for him. No, this can't be happening. And then he got up, and he smiled. I told him, 'Man, you got to quit doing that to me.' "
It was the same knee that cost Maclin the entire 2013 season, and he admitted to being just as scared as everyone else at Lincoln Financial Field who saw him on the ground.
"Yeah, absolutely," the veteran receiver said. "Obviously it was an awkward fall. Very similar to what I did last year with the knee going straight into the ground like that."
Concern for Maclin's well being was the first thought. A close second: Can the Eagles win without him?
We were already asking if they can win without DJax.
Fortunately for the Eagles, they did not have to contemplate that question at all. By the time Foles and the offense went out for the next series, Maclin was ready to reenter the game. Foles was not shy about getting the ball to his top receiver, either. The two immediately connected for a 9-yard gain.
"A lot of ACL injuries happen like that," Maclin said. "Luckily my quad is strong enough, and everything was intact."
With the Eagles in their four-minute offense - aren't they always in their four-minute offense? - just before the end of the first half, Foles found Maclin for another 9-yard connection, which helped set up an Alex Henery field goal that gave the Eagles a 17-0 halftime lead.
It was a great night for the offense, and it continued even after Foles and the first team departed. Foles, after being a little erratic in the early going, completed 19 of 29 passes for 179 yards, a touchdown, and an interception. Maclin, targeted eight times, caught six passes for 43 yards. Cooper, after sitting out the first two preseason games with a foot injury, caught three passes for 25 yards.
"It felt good being out there with Nick and the guys," Cooper said. "I felt like I did some good things and then some stuff I'd obviously like back, but that's every game. I've only had three practices, but I'm getting back into it."
Before suffering his thumb injury, McCoy ran four times for 24 yards and turned a poorly thrown screen by Foles into a 22-yard touchdown. Most important, the X-rays on his sore thumb were negative.
We still do not know if the Eagles could survive an injury to Maclin, or Cooper, for that matter. We do know they don't want to find out.
"I don't think anybody is happy with any depth if you lose a starter," Kelly said. "I'd be sad if we lost McCoy, Foles, Celek, anybody. When he was down I was hoping he was OK, and he was."
The grand offensive scheme is to spread the ball around. You want to take away McCoy, then Foles will find Maclin or Cooper. You want to take away the receivers, then tight ends Zach Ertz and Brent Celek can beat you. Not paying attention to Darren Sproles? That would be a huge mistake, too.
For the first time this preseason, we saw what the Eagles' offense can do with its pieces in place. We won't see it again until opening day against the Jacksonsville Jaguars, but at least it appears as if this will be the same high-powered machine it was a year ago, and maybe something even more.