Jalen Mills fell and either couldn't or wouldn't get up. He eventually hopped up, which was all Jim Schwartz and Cory Undlin needed to see to know the cornerback hadn't suffered an injury.

"Jalen, get up and finish," Schwartz, the defensive coordinator, said from the sideline.

Undlin, who was positioned about 20 yards behind Mills, had harsher words.

"Get the [heck] up and run," the Eagles defensive backs coach shouted.

Mills' effort - or lack thereof - was the perfect opportunity for the coaches to dress down a rookie who hadn't yet faced much adversity. Deep down, Schwartz and Undlin - especially Undlin - had to relish the moment.

"You were on your way up," Undlin said, "now you're on your way down."

Undlin sounded like a drill sergeant delivering an oft-repeated boot camp diss - think Louis Gossett Jr. in An Officer and a Gentleman. But that doesn't mean there wasn't a lesson.

Saturday was the Eagles' first full-pads practice of training camp. Mills has catapulted up the depth chart since being drafted in the seventh round, but he did so in practices that were essentially two-touch football. When the hitting starts, the men start to separate themselves from the boys.

And for rookies, even ones that seemingly have the skills to excel in the NFL, that is often when camp becomes a mental grind. Mills said he got Undlin's message.

"He expects perfection out of everybody in the room - rookie all the way to the top," Mills said. "Him just telling me that - I like it. He's helping me build myself to become the player I want to be and that he knows I can be.

"He always says, 'Hot feet.' If that situation happens on either side of the ball - that time it was me - I just have to get up and keep running."

It isn't very often that a rookie can enter the league and start right away - especially at a position in which you're often left on your own. But the Eagles have an opening, maybe two, and Mills has been making a strong case.

"He still makes rookie mistakes, but he immediately jumps off the tape because his demeanor on every snap is he thinks that he should dominate," Eagles safety Malcolm Jenkins said. "That's half the battle there, regardless if you get beat or not. He wants to compete. He's playing well."

But it's a long way between now and the season opener on Sept. 11. Jenkins was drafted out of Ohio State to play cornerback and started six games as a rookie. But it took 10 games to crack the lineup. He said it's usually the prospects from elite college programs who are able to immediately handle the mental part of playing corner.

"A lot of it comes down to your mind-set," Jenkins said. "If you've got the skill, you'll be here. But the mind-set if you get beat - how can you bounce back, how can you fight through adversity - that's what really separates you as a young player because most guys need to grow into that."

Mills played at that level in college. The Louisiana State product would have been drafted higher had he not been accused of hitting a woman. He maintains his innocence and has said that he pleaded down to a lesser charge to have the misdemeanor expunged from his record.

Nevertheless, it scared many teams away. If the free fall affected Mills' psyche, it hasn't shown. He has consistently made plays on the ball, perhaps as many as any corner since the spring.

He's been running with the second team in camp alongside second-year corner Eric Rowe. Leodis McKelvin and Ron Brooks have been the first-team outside corners, and Nolan Carroll has taken Brooks' place when he slides into the slot in the nickel defense. But no one's name is written in ink.

Schwartz has obvious affection for McKelvin. But Carroll still isn't 100 percent healthy - he left Saturday's practice early with soreness in the same ankle he broke in November. And Rowe has struggled to adapt to the new scheme.

Mills has size (6-foot, 191 pounds), good speed, and the necessary confidence - "You've got to have that swagger," he said. But does he have the off-the-field intangibles?

"I have a love and passion for the game," Mills said. "I'm dedicated to it off the field with my playbook and taking care of my body. . . . I'm willing to learn, whether it's a receiver telling me why he gave me a move, or Jenkins or one of the other guys in the secondary telling me things I can do to put myself in a better position."

He wasn't a ballyhooed tackler in college. "Pretty decent" is how he described his tackling skills at LSU. But Mills had to use different techniques at three different spots - outside corner, slot corner, and safety. Right now, he's focusing on just one.

"You can't play with corners that won't attack the run, and those guys have to all prove that they can step up and thud a running back and go take on a pulling guard at times," Schwartz said. "That's part of their job description."

On Saturday, Mills squared up and didn't back down when rookie running back Wendell Smallwood darted into the secondary. And when veteran receiver Chris Givens tried to seal the backside during a run play, Mills jacked him up.

"We've been going at it," Mills said.

The play was away from Mills, but it didn't matter. He finished. Now he has to finish all the time.