After the Lions released Jason Hunter, Jim Schwartz explained that they made the move to give the defensive end a chance to catch on somewhere else. Because Hunter was losing reps in Detroit and was falling out of the Lions' future plans, simply releasing him now would give him extra time to find a new team.
For Hunter, that proved to be a good move, as he has already signed a deal with the Denver Broncos, the Lions' opponent on Saturday. With Denver, he will likely serve as a depth player and have to compete to make the 53-man roster. Apparently his chances of making the Lions were getting slimmer and slimmer, which is why he was released and given the chance to compete for a spot with the Broncos.
For a look at what Broncos fans have to say about this move, head over to Mile High Report.