Blum suffered a season-ending injury to his elbow in July 2010 while putting on his shirt after a game. He had this to say: "There are probably 90 percent of us in the big leagues that have loose bodies floating around. It just so happens that after the game, it tightened up on me. The shirt had nothing to do with the damn injury."
On November 15, 2010, Blum signed a two-year contract worth $2.7 million with the Arizona Diamondbacks. In 2 years with the Diamondbacks, he appeared in a total of 40 games out of 326 possible games due to injury. He was released by the Diamondbacks on July 20, 2012.