The Oakland Raiders have been one of the most active teams in free agency this offseason and have bolstered both sides of the ball, landing notable top-tier free agents in players like linebacker Bruce Irvin, cornerback Sean Smith and offensive lineman Kelechi Osemele.

Both general manager Reggie McKenzie and head coach Jack Del Rio look to have the Silver and Black pointed in the right direction, making the Raiders one of the sleeper teams to watch out for in the AFC. While Oakland has landed some of the best free agents to hit the open market this offseason, they also lost some key players from their roster, including future Hall of Famer safety Charles Woodson.

The Raiders are still looking to fill the hole left at the free safety position left by Woodson's retirement, but they reportedly met with Pro Bowl safety Reggie Nelson on Tuesday, who would give an immediate presence at the back-end of the Raiders defense. Reports surfaced Tuesday that the Raiders were expected to sign Nelson following a pending physical, but the talented safety left the visit with no deal locked up.

While nothing is reportedly imminent to happen between the Raiders and Nelson, the two sides are likely still working to make a deal happen. The fact that Nelson left the building Tuesday without a deal may not be the best sign, but it clearly hasn't ruled out him landing in Oakland, as he is likely weighing his options.

Nelson would be a huge addition to a defense that already has vastly improved this offseason and would make Oakland's defense one to fear in the AFC. The former Bengals safety recorded 77 combined tackles, defended 14 passes, and finished tied with a league lead eight interceptions during the 2015 season. The veteran safety is heading into his 10th NFL season after spending the six previous seasons in Cincinnati, and he is considered the best free agent still available on the open market.

It's unknown how close the two sides were to a deal in their meeting on Tuesday, but look for this story to continue to develop, as Nelson's addition to the Silver and Black's defense would be a strong exclamation point to a great offseason for the Raiders.