It seems that the Buccaneers don't think Ahmad Black can play deep safety consistently, at least if we can believe the Tampa Bay Times which suggests that the Bucs want to find a starting safety in free agency. According to Stephen Holder, the Buccaneers may not want Ronde Barber back as a safety: they see him simply as a nickel cornerback. That leaves the Bucs with a big hole at safety, and they're likely to use free agency to fill it.
Of significance is the fact that the Bucs are moving forward with plans to sign a starting-caliber safety during free agency. That means Barber likely will be pushed aside after one year as the starting free safety. Whether Barber accepts their terms and returns to the Bucs is hard to predict. The more immediate question might be which safety are they eyeing - Dashon Goldson perhaps?
Essentially, there are three players the Buccaneers could look at in free agency as starters. It's important to remember that for the Buccaneers, their two safeties are not interchangeable. They drafted Mark Barron to primarily play near the line of scrimmage as an enforcer against the run and to cover tight ends man-to-man. To complement Barron, the Buccaneers need a deep safety with range who can handle the deep responsibilities on his own when Barron drops into the box.
In other words: the Buccaneers want a safety who can play as a single-high safety, roaming from sideline to sideline to man the deep responsibilities. This requires a safety who knows when to react to a quarterback's eyes and who simply has the pure speed and quick hips to get to either end of the field. There are only three safeties who can do that in this year's free agency class. Greg Cosell has a tremendous film breakdown of the safeties in this video, but let's go over the realistic options.
This is probably the best option. Goldson is still a young player at 28 years old who has played some very good football over the past two years. He has the range to play the deep safety, more so than I thought initially, and he's aggressive and very solid in run support. He's just a very good all-around safety who would fit nicely next to Mark Barron, and if the Buccaneers are looking for a starter they should mainly be looking at Goldson.
Ed Reed used to be the king of deep safeties. He was a game-changer, someone who epitomized the playmaking ballhawk safety in a deep role. He had the speed to get from sideline to sideline faster than any safety in the game and he has had a Hall of Fame career.
Notice the use of past tense? That's because he isn't that player anymore. He's still solid and he can still fulfill the role the Buccaneers would want, but he's lost some speed, he's not a game-changer anymore, and his run support has really fallen off. He'd be a temporary stopgap, and not much more than that.
As a former cornerback, Quin is an intriguing player. In a sense he's still learning to play safety, but he's gotten better every year. He can do everything a safety needs to do, including covering the deep middle of the field. He may be best roaming around the line of scrimmage, though, because he's so versatile: he can cover tight ends and receivers, he can blitz, he can support the run -- he's a Swiss Army knife. He's a good player and one that can be used in a variety of ways, but if the Buccaneers are looking for a deep safety, this may not be the best place to look.