Middle Linebacker must be the most-discussed position group. Barrett Ruud has been the starter for four years now and has led the team in tackles each of those four years. He has been a leader of the defense and brings a lot of value in coverage while also setting up the defense. Despite that, he has drawn criticism for his lack of physicality.
The Bucs have had opportunities to extend the linebacker these past years, but have not done so, and now he is scheduled to be an unrestricted free agent. No one knows whether he will be back with the Tampa Bay Buccaneers, but my feeling is that he will not be brought back. The Bucs declined to franchise tag him when they could, they have not offered him a long-term contract and have brought in two people who could play middle linebacker immediately: Tyrone McKenzie and Mason Foster.
Tyrone McKenzie may be the most likely to start if Barrett Ruud leaves. He was a third-round pick in 2009 for the New England Patriots, but missed his rookie season with a knee injury and was picked up by the Bucs in 2010. He's spent the offseason working out, he's turned into one of the leaders on the team despite barely appearing on the field last season. McKenzie's known as a hard worker, and he's done everything he could this offseason to be ready to take on a starting role this offseason. But with the extremely short offseason, no one knows whether the Bucs dare hand him that role.
Mason Foster is even less experienced. The third-round draft pick also has a reputation as a hard worker, and appeared at the Bucs' mini-camp last month. Unfortunately, he's a rookie, and largely an unknown for the Bucs' coaching staff. He's very versatile, but has never even seen the field in the NFL. Because of that it's much more likely that McKenzie will be the starter, unless Foster has an amazing training camp. At the same time the Bucs had no problems trusting inexperienced players to start last season, and that didn't really hurt them
If Ruud doesn't return and the Bucs can't trust McKenzie and Foster, they will need to go out and get themselves a free agent. Stephen Tulloch is the big name at middle linebacker. The Tennessee Titan has been good and productive for several years, and should have little trouble fitting right in. The same can be said for Buffalo Bill Paul Posluszny, whose only knock is that he has missed games because of injuries the past two seasons. Behind those two, Philadelphia Eagle Stewart Bradley, San Diego Charger Kevin Burnett and Jacksonville Jaguar Kirk Morrison are all solid players who would fit in this defense.
Ultimately, I think the Buccaneers roll with youth. If they are going to bring in a free agent at middle linebacker, it will likely be Barrett Ruud himself. With two solid young players at the position, the only reason to bring in a free agent is if they don't think they can get McKenzie and Foster ready in time. But the same would be true for any other linebacker brought in, except Barrett Ruud.