Crabtree suffered an Achilles tear last year, but Boldin has stated that the player has looked particularly impressive during the team's mini-camp.
"He's a lot more explosive," said Boldin, according to the NFL's official website.
"I see him being back to his old self. He's taking things slowly. We want to make sure he goes into the season healthy."
Greg Roman will be hoping that Crabtree will be a mainstay in his new-look offense come next season.