49ers coach Mike Singletary said he’s been impressed with second-year WR Michael Crabtree during the offseason workouts. This is Crabtree’s first full offseason after dealing with a foot injury and a holdout last year. “I think Crabtree continues to really carry himself well,” Singletary said. “He works his tail off and is getting the work done that he needs to get done. So, I think Michael Crabtree has had a good OTA, a good minicamp.” The offseason work should help his production, and he should develop chemistry with QB Alex Smith in training camp, which Crabtree didn’t have last season.