Armstead and Buckner bookend defensive line during Monday’s practice

The San Francisco 49ers continue to experiment with the lineup as training camp, which has two days of practices in the books, progresses. While Arik Armstead, Mike Purcell, and Quinton Dial were the defensive line starters from left to right during practice on Sunday, it was DeForest Buckner, Dial, and Armstead during Monday's practice.

That's why the 49ers spent two first-round selections during two consecutive drafts on defensive ends, selecting Armstead in 2015 and Buckner this year. The goal is to improve a defensive pass rush that produced only 28 quarterback sacks last season, as opposed to the 53 that opposing defenses produced. Outside linebacker Aaron Lynch, who is the team's best pass rusher and tied for first on the team last season with Ahmad Brooks in sacks (6.5), is suspended for the first four games.

The 49ers would like to see Buckner and Armstead, two Oregon products who are actually best friends, bookend the defensive line for years to come. While the team has been careful bringing the two along this offseason, Buckner and Armstead have turned some heads during the offseason program and early part of training camp.

Buckner has the lofty goal of winning this season's Defensive Rookie of the Year award. He has been praised during the team's offseason program and many felt that the seventh overall pick in this year's draft would overshadow Armstead, who some considered to be a reach by the 49ers when selected 17th overall last year.

"[Buckner] seems like a lock to start until Glenn Dorsey returns," said Grant Cohn of the Press Democrat on Monday.

Advanced statistics site Pro Football Focus was in love with Buckner prior to his selection in April. "Buckner is the No. 2 player on the PFF Draft Board and the 49ers got a steal at No. 7 overall," said Steve Palazzolo of Pro Football Focus in regards to the selection.

As for Armstead, he has been praised so far in training camp and looks to prove his doubters wrong. Despite his limited playing time last season (384 snaps), Armstead graded 28th overall among interior defenders according to Pro Football Focus. In fact, he graded as the team's second best interior defender going into 2016, behind only Ian Williams, who is now out for the year.

"I think [our defensive line] could be very good," Armstead said Monday via Chris Biderman of Niners Wire. "We have a lot of guys on the D-line that I know can play in the NFL and play good. I'm sure they're going to keep mixing it up. Seeing what best group fits together. And that will be a long process figuring that out."

"Armstead had a particularly strong day, making two 'tackles' in the backfield on running plays," said Matt Barrows of the Sacramento Bee following Monday's practice. "Armstead broke through the left side of the offensive line and crashed – accidently – into running back Carlos Hyde, causing a fumble. A few plays later, the 6-7 defensive lineman again was in the backfield to thwart another running play."

"The 49ers do not tackle during practices, but Armstead had such momentum built up he could not avoid hitting Hyde," said Matt Maiocco of CSN Bay Area in regards to the collision with Hyde.

"The best player on the field today," said Grant Cohn of the Press Democrat on Monday in regards to Armstead.

"For the day, Armstead stood out more than any defensive player out there," said Biderman. "His burst off the line of scrimmage was far better than during training camp as a rookie. His use of leverage looked improved, and he was able to shed blockers with one arm."

Armstead has been itching to throw on pads and go against OT Joe Staley in practice. He will get his first chance this offseason on Tuesday when the team practices in pads for the first time. "He forces you to have good footwork and good anticipation," Armstead said of Staley via the Sacramento Bee.

Barrows also noticed that Armstead, who worked out in Hawaii with Buckner and Seattle Seahawks defensive end Michael Bennett during the team's time off following June minicamp, looked in better physical shape this season.

While the loss of Williams certainly hurts the 49ers defense, the emergence of Armstead and Buckner could improve the team's pass rush for years to come.