OXNARD, Calif. -- It all looked so strange.

On one field, there was Taco Charlton, in full uniform, running sprints back and forth in the end zone with a strength and conditioning coach. On the other, the rest of the Dallas Cowboys defensive linemen were going through individual drills, slapping blocking dummies left and right.

Sometimes as he rested, Charlton looked over to see what was going on with his linemates.

Later, as team drills took place, Charlton had a belt tied around his waist and went through resistance training.

The unofficial word on Charlton's absence was "tightness," but the tightness of what was never defined. After practice, Charlton stopped briefly to meet with the media.

Asked if his legs were tight, he said, "I'm good. I'm good."

Asked what he was dealing with, he said, "I'm good."

Asked why he didn't do team drills, he said, "I'm good."

He may very well be "good," but it all came across as odd, seeing the Cowboys' first-round pick working off to the side. In Tuesday's practice, he did not appear to be laboring at all. He spoke after the workout mostly about Tyrone Crawford's ankle injury. He has not missed a practice in camp yet, either.

It was as odd as seeing Charlton playing only two series in the Hall of Fame Game against the Arizona Cardinals. Why not wear him out, give him a ton of work, see how he fares, perhaps build some confidence?

"We felt like he had a good number of snaps in this game," Cowboys coach Jason Garrett said after the game. "I don't know the exact total right now, but he's going to get plenty of snaps as we go forward."

Asked about Charlton's work so far?

"Taco's learning," Garrett said.

Every rookie has a learning curve with how things work in the NFL. In Charlton's welcome to his first training camp, he has been lined up a lot of times against All-Pro left tackle Tyron Smith. That's difficult for even the best pass-rushers in the NFL. At times he has worked against right tackle La'el Collins and ended up on the ground.

On Tuesday, Charlton twice was called on to perform in the compete period against undrafted offensive lineman Nate Theaker. He tried a spin move the first time and likely would have forced a penalty. On the second snap, Theaker handled the bull rush with ease.

"It's really important for college players to understand how we do things in the NFL, how we do things for the Dallas Cowboys," Garrett said. "We’re going to give them plenty of opportunities to understand that. And we're going to coach them. We're going to give them a lot of feedback, positive feedback and negative feedback, and let them know what the standard is for everything that we do. So for Taco, and for all the guys we drafted and all the new guys, that's what the daily process of training camp is."

What made Wednesday's circumstances strange was this opportunity presented by Crawford's absence. The ankle injury is likely to keep him out for the rest of the offseason, with Crawford hopefully returning for the Sept. 10 regular-season opener against the New York Giants.

With the suspensions of David Irving (first four games) and Damontre Moore (first two games), the Cowboys are going to need everybody and anybody to rush the passer. They drafted Charlton in the first round to be one of those options. His sack total rose every year at Michigan. He had dominating performances, like the Ohio State game in which he could not be blocked.

So far in camp, Charlton has had moments, just not consistently. He slipped through two offensive linemen to force a tackle for loss on Monday. In one-on-one drills, he won with a spin move on one snap and a power move on the next. It was his best practice.

But defensive coordinator Rod Marinelli, who doubles as the defensive line coach, admits things are never good enough, regardless of the player.

"It's the details of your hands, the suddenness," Marinelli said. "He's coming off the ball. Now it's just getting ... young guys have a tendency when they rush to start looking up and seeing what's going on in the backfield, and a guy's got a big paw in your chest. It's about the details as you’re rushing, getting the hands, being precise. The precision of everything they do. They have to do a lot of things, but be precise."

Marinelli is demanding. There are a lot of tough-love moments. But Charlton doesn't mind.

"He just brings the best out of you," Charlton said. "That's what you want as a player. I hope that's what you want as a player. It's not hard. He just pushes us and pushes you to be the best."

Charlton was not sure if he would practice Thursday. He needed to talk to the trainers. He is looking forward to the second preseason game, Saturday's matchup against the Los Angeles Rams, but he doesn't how much he will play.

"I'd say every day is an improvement, no matter where I am," Charlton said. "I'm trying to improve every day. I've made a lot of progress from where I started and I've done some good things."