The Oakland Raiders started the league year with one of the highest salary cap spaces in the league, and the Raiders front office and general manager Reggie McKenzie have wasted no time in bolstering their roster signing some of the NFL's top free agents.

The Raiders front office has reportedly already landed top free agent offensive lineman Kelechi Osemele and reached an agreement with former Seahawks linebacker Bruce Irvin to join the Silver and Black's defense. The Raiders were one of the most improved teams during the 2015 season and are only looking to develop a stronger roster after landing some of the top free agents on the market.

The team's secondary will miss one of the all-time greats in free safety Charles Woodson, but its front office has continued to focus on building on their pass defense and has reportedly landed cornerback Sean Smith. The 28-year-old corner has reportedly signed a four-year deal worth $40 million, which includes $20 million guaranteed.  

The former Chiefs corner recorded 45 combined tackles and two interceptions last season, but he was suspended for the first three games of the season due to a DUI charge that he pleaded guilty to in 2014. The 6-foot-3 newly acquired corner is expected to play opposite of corner David Amerson, and many believe that the Raiders defense will continue to improve in 2016.

The Raiders have their franchise quarterback in place with Derek Carr, and are building strong foundation in Oakland, as they look to be only getting stronger on both sides of the ball. The Raiders defense gave up the 22nd most points in the NFL last season, and their front office is clearly focused on protecting their young franchise quarterback while also building a strong defense.

It will be interesting to see how Smith fits in Oakland's secondary, but the former second round draft pick is looking forward to joining the Raiders in California and has already changed his Twitter account to defensive back for the Oakland Raiders. In seven seasons in the NFL, Smith has defended 83 passes and recorded 10 interceptions, and he will look to continue to be an impact playmaker in Oakland's secondary in 2016.