When Callahan is on the field he is an elite nickel corner. Stats don't lie. The only problem with Callahan is his ability to stay on the field.LOL! You need to stop saying this shit cause it isn't true. Elite is All Pro level of play every single year. This is not Callahan.
But I digress, I am of the opinion that the SS position is less of a concern when you have a player of the caliber of Eddie Jackson. Create competition with Deon Bush and have a camp battle for the spot with two younger, cheaper options and use the money elsewhere.
Personally, I think Callahan's injury history could make him a value signing - when he is on the field, he will outplay any dollars he does get because that injury tag will hurt his value. With Callahan I get elite production while with Amos I get average/above average production depending on the day.