The Eagles traded up to draft Cox, a move that received near-unanimous praise at the time. Even the doubters jumped on board after a promising rookie season in which the then-defensive tackle recorded 51/2 sacks.
But Cox didn't have the breakout sophomore season that screamed "future Pro Bowler," as many had predicted he would. He was good, often great. But a scheme change limited the opportunities for individual achievement, and it seemed to affect his play for stretches. He finished with three sacks.
Like most of the starters on defense, though, Cox believes that having another year in coordinator Bill Davis' two-gap, 3-4-leaning defense will pay dividends in what could be a make-or-break season.
"Basically, it's got to be one of my better years this year, my third year going in," Cox said Sunday. "I've got two years under my belt. Hey, I'm ready to take off."
But will the Eagles allow more chances for Cox to play to his strengths as a one-gap penetrator on passing downs? The Houston Texans and San Francisco 49ers, for instance, have catered their 3-4 hybrid defenses to the pass-rushing strengths of J.J. Watt and Justin Smith.
"You never know," Cox said. "It depends on the situation and what defense Coach Davis is calling. Basically, it's sacrificing and being committed to helping the guy next to you."
Cox has got to make a significant jump, though, if he wants to be mentioned in the same breath as Watt or Smith. Defensive line coach Jerry Azzinaro was asked about Cox and his 2013 performance, but rather than answer specifically about him he focused on the entire defensive line.
"I think those guys are getting there," Azzinaro said last month. "It's a work in progress."
Asked several times to single out a defensive lineman last season, coach Chip Kelly often praised defensive end Cedric Thornton. He once said Thornton was his best rushing lineman, even though he played far fewer passing downs and generated far less pressure than Cox.
It's difficult to compare Cox's statistics as tallied by the coaches in his first two seasons because of the different staffs. But his numbers, according to Pro Football Focus, increased only marginally despite his playing 46 percent more in 2013.
As a rookie, Cox, per the website's evaluations, recorded six quarterback hits, 14 hurries, and 24 tackles. Last season, he notched 10 hits, 39 hurries, and 32 tackles.
But defensive ends playing effective two-gap football - responsible for the gaps on both sides of an offensive lineman - aren't often going to be rewarded on the stat sheet.
Asked how he measures success for his linemen, Azzinaro said, "If they perform their techniques and fundamentals consistently."
Azzinaro focuses on the power of repetitive action. He teaches his linemen the proper technique for, say, how to play two-gap defense against the run - strike the lineman, see the ballcarrier, and react. And this is how they practice over and over.
Cox played more instinctively in college and his first NFL season, using his aggressiveness and athleticism to shoot past blockers and make plays. Davis' base defense requires the linemen to take up blockers and free up the linebackers to make tackles.
If Cox or Vinny Curry, another defensive end who is better suited to play one-gap, were to penetrate rather than "strike," the integrity of the scheme would be disrupted.
"You've just got to beat the guy in front of you," Cox said. "Being asked to do a few different things - that comes with playing in the NFL. Coaches ask you to do a lot of different stuff. That's the task. Go compete."
There may be questions about whether he is a long-term answer at 3-4 defensive end or if the Eagles even intend on spending a high percentage of their salary cap on an unglamorous position.
But Cox knows what Davis and Azzinaro want now. It's his job to carry it out.