As everyone knows, when Jake Ballard becomes a potential player again in 2013, he will be a Restricted Free Agent, as he'll gain that status after this year.
Under the new Collective Bargaining Agreement (CBA), signed between the NFL and its players before the last season began, there have apparently been no RFA's that have switched teams this year, despite the lessening compensation than was the case under the old CBA.
Mike Florio wrote of 42 players categorized as such this year and no signings by other teams.
So, another unwritten rule may be in effect (like the one that usually lets an injured player like Ballard clear waivers) that also has NFL teams not taking RFA players off the hands of other teams.
Don't count on that in 2013 with Ballard. The Patriots may be forced to match a qualifying offer that the Giants make to Ballard. As a matter of fact, I'd tentatively predict that this will happen, and at the very least, Ballard is by no means a Patriot on the field yet.
Of course, much depends on Ballard's recovery.