Like every season, training camp always brings the start of something new and the end of something old. Veterans who are too veteran may find themselves unemployed (see Rudi Johnson of the Bengals) and new rookies may either take a job from another player or never see the light of an NFL day outside of the training camp environment.
Several well known sports journalists have speculated who are "on the bubble" from AFC North teams. While some is speculation and intuition, there are many players who have come to join this list because they have either failed to materialize or wore out their welcome.
For a similar perspective: See Kevin Walker of ESPN.com.