Free agency starts at 4 p.m. ET (1 p.m. PT) Tuesday.It is clear the San Francisco 49ers' plan of attack will be to sign their own top free agents. They secured their top free-agent priority, receiver Anquan Boldin, last week. Their other targets are safety Donte Whitner, cornerback Tarell Brown and kicker Phil Dawson. Dawson and Brown both may get quick action on the open market.If any of these players leave, the 49ers will likely have to go find a replacement in some form.