SANTA CLARA - The 49ers brought in plenty of defensive reinforcements this offseason to bolster a starting rotation that has played nearly every snap the past two seasons.After trading down in the second round, the 49ers selected Florida State defensive end Tank Carradine, 6-5, 273 pounds, with the 40th overall pickLineman Quinton Dial (90) is one of several 49ers rookies to agree to contracts on the eve of their first minicamp.