The Sam spot is the biggest area of need, IMO. Black is by far the worst LB and the worst of any position on the team.
The SAM spot on the Bucs has been a 2 down or less position for years and is also the least important position on the defense as far a having a quality player in that position.
That said.....overall....until the Bucs figure out how to get the front 7 to play well consistently...even dominate....the defense is going to struggle. They can't put any more resources from the draft into the DL. So a high end pick at LBer is almost a must.