On Monday it was reported that Patrick Willis and Justin Smith would be retiring this week, which leaves two important vacancies on the defensive side of the ball for the San Francisco 49ers. Does this change the team's draft strategy?

Both ESPN Insiders Mel Kiper Jr. and Todd McShay have the 49ers selecting Oregon defensive end Arik Armstead with the No. 15 overall pick. In 13 games with the Ducks in 2014, the junior recorded 46 tackles (5.5 for loss), 2.5 sacks and one forced fumble. His size (6' 7" and 292 pounds) and agility is what has many clamoring over his potential at the NFL level.

"Armstead is a great value pick [for the 49ers] at this spot (he's our No. 9 overall player), with an outstanding combination of size, agility and power," writes McShay. "He shows violent hands to get off of blocks in the running game and as a pass-rusher. The arrow is pointing the right way with him, and he could be the heir apparent to Justin Smith, who is considering retirement."

Although the team just signed defensive lineman Darnell Dockett, they're still going to need some depth and good competition heading into training camp.

But Armstead will only fill one glaring need, while the inside linebacker position could use an upgrade. Willis and Navarro Bowman were once considered the top inside linebacker duo in the game, but injury issues didn't give them a chance to further prove that in 2014 and now Willis is hanging up his cleats. Bowman will be ready to go in 2015 and it's possible one of the free agents on the market (Brandon Spikes, Mason Foster, Rolando McClain and others) may join him.

However, the 49ers have other needs on the offensive line and defensive backfield, so perhaps they aim to fill those vacancies in free agency instead. Another name they could be after in the draft is Miami inside linebacker Denzel Perryman, who is ranked No. 32 on McShay's big board. He's the top inside linebacker in the 2015 draft class and could now be of interest to San Francisco.

"He's physical and plays angry at the point of attack," an AFC East regional scout told NFL.com. "He's the type of guy you like having on your team because he brings toughness to practice. He's going to lay the wood to ball carriers when he gets a chance but college teams were already finding ways to go after him in the passing game."

The 5' 11" 236-pound linebacker showcased his talents when it mattered most - during his senior season at Miami. He recorded 110 total tackles (9.5 for loss), two sacks, three forced fumbles, one interception and five passes defended in 13 games last season. He might be able to immediately replace Willis as a good run defender, but it looks like he'll need to work on his ability to cover in the open field.

Nonetheless, he remains an option for the 49ers because his display at the combine may prevent him from cracking the first round. We'll have a better idea of San Francisco's plans once free agency kicks off tomorrow.