The case against keeping Tony Richardson can be summed up in two words, "John Conner." The Jets drafted the fullback from Kentucky in 2010 to eventually replace Tony in the starting lineup. He is younger, and his contract number will be below the veteran minimum required to keep Richardson assuming the new CBA keeps something close to the current minimum salaries in place. Richardson served as a mentor for the first year, showing the rookie the ropes. Conner should be ready to take over as a starter in 2011.
Carrying two fullbacks is not a necessity in the NFL. Many teams keep one. If the starter goes down, a team can plug in a backup tight end since the two positions have similar responsibilities.
For the past two offseasons, resigning Tony felt like a necessity. The team had not addressed its long term situation at fullback. After selecting Conner, the future is now set. It might be time to go forward.