Hey, they're not exactly household names, but the Bucs continue to add depth to their defense.

   Tampa Bay announced the signing of four free agents Tuesday. The most recognizable player is cornerback Sammy Davis, a first-round pick (30th overall) of the San Diego Chargers in 2003 who was traded to the 49ers last season.

   The Bucs also offically announced the signing of 49ers free agent defensive tackle Lance Legree, former Raiders defensive tackle Kenny Smith and receiver Levon Thomas, a member of the Saints practice squad the past two seasons.

   Meanwhile, former Titans guard Zach Piller visited the Bucs on Tuesday, but the team has not offered him a contract. Piller, who was born in St. Petersburg, has started 58 of 87 games in the NFL.

   The Bucs have expressed an interest in Broncos guard Cooper Carlisle, but no visit has been scheduled, according to his agent Frank Murtha.    

   Legree played in 76 games with 25 starts as a member of the Giants (2001-04), Jets (2005) and  49ers (2006). His career stats include 138 tackles, seven sacks, one forced fumble, one fumble recovery and one pass defensed.

   Davis could have the biggest impact. Last season, he played in 12 games with one start, totaling 30 tackles and eight passes defensed. He has three career interceptions, one forced fumble and one sack. The Bucs re-signed cornerbacks Phillip Buchanon and Torrie Cox. With Brian Kelly expected to return from a turf toe injury next season, there should be a pretty good battle for the nickelback spot between Juran Bolden, Buchanon, Davis and Cox.

   Finally, a bit of irony. Fired Bucs defensive backs coach Greg Burns has been hired to coach the same position with Kansas State. Burns replacement, Raheem Morris, was the defensive coordinator at K-State last season.