The Giants acquired Rivers from the Cincinnati Bengals in exchange for a fifth-round draft pick (which the Bengals used to pick Boise State safety George Iloka in April). Rivers was available for such a cheap price because he missed all of the 2011 season with a wrist injury, lost his starting job to Thomas Howard, and had a high salary ($2.16 million) entering the final year of his rookie contract.
Where Rivers will play in New York has yet to be determined. Rivers played on the outside while with the Bengals and has been working there during OTAs -- however, he's been with the second unit, behind Michael Boley. Rivers also has been rumored to be an option at middle linebacker, where Chase Blackburn and Mark Herzlich are presently first and second on the depth chart.
Until Rivers carves out a role for himself, Reese will continue to have a clear rap sheet.