During the bye week, starting safety Clinton Hart was cut. Now, a league source tells us that cornerback Antoine Cason, the team's nickel back, has been taken out of that role. Per the source, Cason will be replaced by safety Steve Gregory. Cason, a first-round pick in 2008, hasn't committed any obvious blunders. In fact, he leads the team with two interceptions in five games. The problem with the San Diego defense, by all appearances, has been the inability of the front seven to generate a pass rush, along with so-so play from the safeties. So moving one of them to nickel corner in passing situations doesn't make a whole lot of sense.