Throughout OTAs and minicamp, just about every NFL team got a first look at how their top draft pick competed against returning veterans.

The Tampa Bay Buccaneers saw Jameis Winston throw passes to Mike Evans. The Oakland Raiders watched Amari Cooper try to beat Charles Woodson downfield. And the New York Jets had Leonard Williams rush against linemen like D'Brickashaw Ferguson.

Gaining that kind of experience before reporting to training camp is invaluable for incoming rookies, as Williams, the No. 6 overall pick in this year's draft, recently told ESPN.

"Going into rookie camp, I was kind of nervous," Williams said. "But after going through OTAs and minicamp, it definitely built my confidence up a little bit."

But while those players were adding up practice reps, Arik Armstead – the San Francisco 49ers top pick and 15th overall selection in 2015 – could only watch from afar.

An NFL rule prohibited the Oregon product from participating in San Francisco's offseason program until his university's final exams were completed. And by that time, mid-June, the 49ers had already broken camp for the summer.

While away from the team, Armstead trained by himself and studied the playbook and practice film on his iPad. Now set to embark on his first NFL training camp, Armstead hopes the offsite work will help shrink the expected learning curve.

"I think I'm going to be just fine," Armstead said on Friday. "Defensive scheme-wise, I'm picking up everything well. It's pretty similar to what I did in college.

"And training camp will help me get my body into better shape and get me used to the movements of football again. I'm a little behind because I missed some things, but I'm excited to make those gains in camp."

What was the hardest part of the wait for Armstead? Not being able to show his new employer what he can do.

"I'm a competitor," Armstead said. "I love playing the game of football. And now I'll be playing against better people, so it's going to be a test of how I can adapt to it. But there's unlimited film to study and people to watch, so I'm excited to be here and see where I go in my career."

Armstead said the team is happy with his weight, which has remained between 295-300 pounds since his senior year in high school. The 49ers plan to give the rookie d-lineman reps at both defensive tackle positions, something the coaching staff is confident that he can handle.

"I'll tell you what; I've been really encouraged with Arik. I really have. Everybody has," Jim Tomsula said. "Arik is in great workout shape. What you miss is the eight-second explosions of a play. But mentally, he's doing a really good job. He's got everything picked up."

Added defensive coordinator Eric Mangini: "What I liked about Arik is while he was gone, he was still looking at the information. It's not like he came into the classroom and was lost. He's another guy that's very conscientious. It looks like he's going to be outstanding in terms of his work ethic."

At this point, it's far too early to predict what kind of impact Armstead might have in his rookie campaign. The 49ers are stacked across the d-line with players like Darnell Dockett, Glenn Dorsey, Quinton Dial, Garrett Celek and Tony Jerod-Eddie all competing for snaps at defensive tackle.

"We have a real good, talented group," Armstead said. "It's a good mixture of young guys and talented vets. I'm excited to be a part of it. I'm trying to soak up as much knowledge as I can. I know that's going to help me in training camp and preseason and then into those real games."