Bill does hold a certain affinity for Freeney and Mathis, and should any of them hit the open market I'm certain he will at least give them a look.
But consider who currently comprises the DE Depth:
* Marcus Benard
* Jake Bequette
* Jermaine Cunningham
* Justin Francis
* Chandler Jones
* Rob Ninkovich
Chandler Jones was a monster before spraining his ankles, and with another training camp under his belt he should be primed for a breakout year. Until proven otherwise or unless the Pats get someone who blows them out of the water, Jones is a starting DE on this team.
Rob Ninkovich took another step forward in his career this year. It seems with each season he gets better and he has a knack for coming up when a clutch play is needed. The only knock in him is his size, as Ninkovich is a bit undersized (though so is Dumervil, but nobody is talking about that). In any case, the coaching staff needs to decide what Ninkovich's role will be going forward. As a starting DE? Starting LB? Rotational DE/LB for pass rushing situations? If there is an upgrade to be had, it could be at Ninkovich's DE spot, moving him to a more rotational roll. Nonetheless, Ninkovich is proving his worth and needs to see the field.
Cunningham and Francis are interesting because they're tweeners, able to switch between DE and DT depending on the package and situation. Cunningham started strong before being suspended and was replaced by Francis, who has flashes against the Dolphins but was otherwise very quiet.
Bequette and Benard are the two Proven/Unprovens. Bequette was a productive rusher in College but has yet to break through, perhaps this will be his year (though at who's expense?). Benard has had NFL experience before and has been productive, though injuries have forced him to bounce around the league.
In short, if any Defensive Ends are to be added to this team, they need to be of starting caliber or are able to specialize in getting after the passer from anywhere along the line (NASCAR Package).
Jones and Ninkovich go into the next season as the starters, with presumably Cunningham and Francis as the top backups (unless Bequette or Benard flash promise). If a Freeney (or any other Veteran DE) would be acquired or drafted, they need to be able to contribute and not just add to the endless pile of medicoracy.