According to the Tampa Bay Times, the Buccaneers have not started contract talks with free agent nose tackle Roy Miller yet. Miller had the best year of his career last season, finally showing consistently why he was a third-round pick in 2009. His quality season didn't actually show up in his statistics, as he posted career lows in every single stat except pass defenses, but he was instrumental to the Buccaneers producing the best run defense in the NFL. So why would the Bucs not try to re-sign him yet?
The answer to that question is fairly easy, really. For one, they are focused on re-signing Mike Williams, and should be making defensive end Michael Bennett their biggest priority before free agency proper starts. But there's another reason: for all of Roy Miller's quality play, and he really was very good against the run, he is still completely useless against the pass. That's unfortunate, because his work against the run was crucial, but it depresses his value and makes him relatively replaceable.
Which is why we really didn't see a big drop-off in run defense when Gary Gibson came in. Roy Miller played just 46% of the defensive snaps on the year, and while he was good and the Bucs are likely to want him back, they're more likely to sit back and let him sniff the free agent market. If he becomes too expensive, they'll simply let him sign elsewhere. And if not, they're probably going to welcome him back.
Because that is what good teams do: they let those players they can replace walk, and then replace them with cheaper alternatives.