Gaither joined the Chargers after getting cut by the Chiefs last season and San Diego signed him to a four-year contract in March. Back problems helped cause his departure from Baltimore after the 2010 season. Mario Henderson, who didn’t play in 2011 after showing up to Raiders camp out of shape, has stepped in for Gaither. That underscores how crucial a healthy Gaither is for the Chargers this season. They haven’t gotten one yet and they may have to scramble for further help if Gaither can’t start staying on the field for two consecutive days. *We will be watching this one closely.