The Atlanta Falcons could have as many as three new starters in their secondary against San Francisco on Sunday, perhaps lessening the defense’s ability to take advantage of major changes on the 49ers’ offense. The Falcons held out five players in Wednesday’s practice, including three defensive starters: safety William Moore (groin), linebacker Justin Durant (calf) and cornerback Robert Alford (groin). Cornerback Desmond Trufant was limited after leaving last week’s 23-20 overtime loss to Tampa Bay with a lower back injury.