The Philadelphia Eagles have used the franchise tag on wide receiver DeSean Jackson and have expressed the wish to sign him to a long-term contract. This means two things: DeSean Jackson is off the free agent market, but he is available for trade. It seems extremely unlikely that the Buccaneers would be willing to part with a draft pick for DeSean Jackson, at least one of enough value for the Eagles to accept.
But the Buccaneers do have a need at wide receiver, as the position group as a whole underperformed last season. Issues with route running, gaining separation, speed and, tragically, actually catching a football plagues the entire group of receivers - except for Preston Parker. The Bucs could have addressed one of those issues - the lack of speed - with DeSean Jackson, but that option seems to be out now.
But they do have other options in free agency. Mario Manningham has repeatedly been connected with the Tampa Bay Buccaneers, but better players are available in free agency as well. Most notably Vincent Jackson, who is likely to actually hit the market. Dwayne Bowe and Wes Welker are likely to be franchise tagged, and won't be available - but Marques Colston, Brandon Lloyd, Stevie Johnson, Robert Meachem, Pierre Garcon and others will most likely hit the market. The Bucs can bolster their receiving corps in free agency, but they won't do that with DeSean Jackson.