After watching his defense get picked apart all last season, Oakland Raiders general manager Reggie McKenzie made a priority this offseason of upgrading that side of the ball.

McKenzie spent most of his draft finding defensive reinforcements for the bevy of veterans already added through free agency.

"We just want to be a better defense," McKenzie said. "We attacked that this offseason."

The Raiders spent all five picks on defensive players on the final day of the draft Saturday after previously using their first-round pick on pass-rushing linebacker Khalil Mack.

The Raiders took Louisiana Tech defensive tackle Justin Ellis and Utah cornerback Keith McGill in the fourth round, and Ohio cornerback and punt returner T.J. Carrie, Illinois State defensive end Shelby Harris and Western Kentucky safety Jonathan Dowling in the seventh round.

Oakland earlier drafted quarterback Derek Carr in the second round and guard Gabe Jackson in the third as Oakland continued an offseason goal of adding more size on both lines.

"It makes us a bigger, stronger and hopefully more physical and dominant team," McKenzie said. "We want to do the pushing around, and you do that with big people."

The Raiders allowed the second-most points per game (28.3) in franchise history in 2013 in their second straight four-win season that extended their playoff drought to 11 years.

Oakland signed free agents Justin Tuck, LaMarr Woodley, Antonio Smith and C.J. Wilson to bolster the defensive line and added cornerbacks Carlos Rogers and Tarell Brown.

The team made its biggest move on defense by taking Mack with the fifth overall pick in the first round on Thursday night and then added some depth on the final day of the draft.

Ellis has the flexibility to play either nose tackle in a 3-4 defense or inside tackle in the 4-3 defense that Oakland uses. He made 48 tackles last season, including 5½ behind the line of scrimmage, and is being counted on as a run-stopper.

The biggest concern for Ellis is his weight, which reached 390 pounds at one point in college. Ellis said he weighed about 346 pounds right now and would ideally be at 330 for the season.

"It's been a grind because I'm a built guy just naturally," he said. "I'm a naturally built guy. I gain weight easily but I also lose easily, too, so my weight fluctuates. At the same time, it's been a grind, but it's something that I can do. I haven't lost control of it. But I have gained weight but I also lose it."

McGill played both safety and cornerback in college and had 12 pass breakups his senior season and returned an interception for a touchdown. He allowed 29 completions on 59 passes his direction last season, according to game charting by STATS.

McGill missed the entire 2012 season with a shoulder injury and also had off-field problems with an arrest for DUI and possession of stolen property. But he said he sat down with his coaches and decided to make changes in his life that helped lead him to the NFL.