Must might be the wrong word in this intriguing scenario.
Aqib Talib is the team's top free agent and the Patriots player most likely to command top dollar. If he demands something like a $27-30 million dollar guarantee (above what players like Johnathan Joseph and Brandon Carr got in 2012) then the Pats should let him walk.
But if other teams are scared off by his injury history and off-the-field issues, the Patriots may be able to get him at a reasonable deal.
Talib has been a model citizen in his time with the Patriots and has played very well, especially in the first half of the 2013 season, when he shut down top receivers like AJ Green and Julio Jones.
His hip issues cropped up again as the season progressed, costing him time and hampering his performance in the second half. Still, his ability to play man defense against top receivers makes him incredibly important to the Patriots defense.
The Patriots do have two promising corners in Alfonzo Dennard and rookie Logan Ryan, but without Talib they lack a shutdown corner who can reliably slow top receivers.
The 2013 AFC Championship loss to the Ravens proved how much the Pats need Talib as Anquan Boldin picked apart Marquice Cole. If the Pats let their top corner walk, their finally-promising secondary will take a huge hit.