Please consdier (sic) the words actually written in your responses: "Barry Sanders walked away and not because the Lions forced him into retirement or ruined his career."
Barry Sanders made the choice to leave. The Lions did not force him out. If he thinks his career is unfulfilled and wanted to play longer, he should have A) never signed the extension with the Lions in the first place, B) honored his contract and continue to play for the Lions, or C) request a trade from the Lions. I have no idea if he actually did request a trade or if Ross would have granted it.