I think we've got bigger bait to snare with Mare. Carr is on the verge of being released. Nobody wants anything to do with his current contract. Green is edging on release as well, but Miami have agreed to use their second 7th round pick on him if Miami and Trent can agree on an equitable paycut.
Olindo Mare is more valuable than either guy right now, because his contract salaries are reasonable relative to the ones he could be getting if he were to get caught in a bidding war in free agency.
And as per a source close to the Browns, talks between Cleveland and Miami have been "steadily advancing". So, I think we can bait a bigger fish with Olindo right now. Just continue to offer that late 7th for Green, work on getting he and his agent to accept something close to the veteran minimum with a few incentives...and offer nothing for David Carr.