The Oakland Raiders have retooled their offense over the last four days, as General Manager Reggie McKenzie and Head Coach Jon Gruden have been hard at work building the 2018 roster. When the NFL free agency period opened Wednesday, the Silver and Black waited patiently, while several teams around the league aggressively pursued some of the league's most expensive free agents. Thursday, McKenzie and Gruden pounced, signing seven free agents, adding three more Friday, but they weren't done just yet. Saturday, the team signed another pair of defenders to assist defensive end Khalil Mack and Co.

In case you've been unable to keep up with all the news, you can always check the free agency tracker, but let's take a closer look at the team's moves over the last few days.

Signed:

Wide receiver Jordy Nelson –easily the Raiders biggest free agent signing thus far, Nelson has totaled 7,848 receiving yards, 69 touchdowns, and 550 receptions over the course of his nine-year career.

Running back Doug Martin –a native to the Bay Area, Martin returns home after spending the first six seasons of his career in Tampa Bay. The former Boise State Bronco has rushed for more than 1,400 yards twice in his career.

Tight end Derek Carrier –If there's one thing Gruden wants to do on offense it's to be physical up front. Carrier is known for his blocking prowess as a tight end, and alongside fellow tight end Lee Smith who also prides himself on his blocking ability, the two should combine for a solid one-two punch.

Tight end Lee Smith –speaking of Smith, the 6'6", 265-pound brute is returning to don the Silver and Black. Smith has been a member of the team for three years, and has established himself as a locker room favorite among his teammates.

Fullback Keith Smith –Like I said earlier, Gruden wants to bring a physical brand of football to the Raiders, and the addition of Smith adds to that. Playing in front of physical back Marshawn Lynch, who is returning, Smith will look to bully a path for No. 24.

Linebacker Tahir Whitehead –It's no secret the Raiders needed to address the position, and the team did so by acquiring Whitehead. The former Detroit Lion has tallied 100-plus tackles in back-to-back years, and at 27 years of age he's got some quality years ahead of him.

Cornerback Rashaan Melvin –The former Indianapolis Colts cornerback is coming off arguably his best season; he totaled 13 passes defensed, and three interceptions.

Defensive lineman Tank Carradine –Carradine joins the Raiders after spending time with the other Bay Area team, the San Francisco 49ers. At 6'4" and 276 pounds, he should provide a quality presence in the middle of the defensive front.

Linebacker Kyle Wilber –Don't forget about special teams, it's equally one of the most important phases of the game, and Wilber will serve nicely in Special Teams Coordinator Rich Bisaccia's group. The two spent time together in Dallas.

Safety Marcus Gilchrist –Once a member of the rival San Diego Chargers, Gilchrist joins the Raiders after spending last season with the Houston Texans. He's totaled 11 interceptions, 32 passes defensed, and five forced fumbles in his career.

Long snapper Andrew DePaola –During his four seasons in the NFL, DePaola has played in all 16 games each year, failing to miss action. He spent 2017 with the Chicago Bears.

Quarterback Josh Johnson –The Oakland-native is cousins with Marshawn Lynch, and has been a veteran in the league for years. He's overjoyed to be joining forces with his hometown team.

Punter Colby Wadman –The team also added Wadman, a former punter at University of California Davis.

Released:

Last week, the Raiders released veteran wide receiver Michael Crabtree. The former Texas Tech Red Raider spent the last three years with the team, hauling in 232 receptions, adding 2,453 receiving yards, and 25 touchdowns. Crabtree has decided in free agency to join Joe Flacco and the Baltimore Ravens in the AFC North. He'll face off against the Raiders in Baltimore next season.

Trade:

The Raiders also traded dynamic wide receiver Cordarrelle Patterson to the New England Patriots. The team also gives up a sixth-round pick in return for the Patriots fifth-round pick.