No one jumped on him because he's a starter and by the time the Panthers released him, every team already had their guy. No one wanted to bring him in as a backup because he would put too much pressure on the starter.
If he's playing in NE for peanuts on a 1 year prove it deal, why wouldn't he have played in Carolina for $20M on a 1 year prove it deal? Of course he isn't gonna just agree from the start. He wants more guaranteed money - like every other player - ever. But if they held tight and explained he had to prove himself, he obviously would have. He's doing it now.