Blum injured the oblique while swinging a bat on Tuesday night during batting practice and was placed on the 15-day disabled list.
"Just last swing of my third round of BP the other day," Blum said. "I felt it pop and tear, and sure enough tore it. Never, this is the first time I've had that injury. Hurts like [heck]."
Blum spent most of the 2011 season on the disabled list due to a right knee injury and a fractured right pinkie finger. The two injuries cost him 127 games last year.
"They said it was a pretty good tear or strain or whatever you want to call it, and we're just going to play it day by day," Blum said. "Obviously, [I'm out] 15 days, but I've heard anywhere from four to eight weeks, so it just depends on how I respond to the treatment."
The injury just adds to the frustration Blum has felt since signing a two-year deal with the D-backs prior to last season.
"The only person I can be mad with is myself, but it's just one of those freak things," Blum said of the injury. "It has nothing to do with how I train or what I eat or drink, it's just one of those things that happens in baseball."
And it's happened too often lately for Blum's liking.