For every action, there's an equal and opposite reaction. Isaac Newton's third law of motion is a driving force in NFL free agency.
The majority of acquisitions made at the beginning of the league's new year resulted in a team filling a need from another player being released, leaving to sign with another or both.
There are other instances where disappointing performances from current starters forced organizations to upgrade their respective positions.
A glimmer of hope still exists for these once-highly regarded individuals, yet their luster is starting to dull.
Former first-round picks, fantasy darlings and reliable veterans are now in jeopardy of losing their starting jobs due to recent free-agent signings.