I was looking into it, and on John Sickels' site I found in his Top 20 Prospects review:
13. Brian Snyder: Extended spring training, rib cage injury.
And according to the official Minor League Baseball website, he had exactly two plate appearances and walked once for the "AZL Athletics". It doesn't say when those two PA's were.
It sounds like he got hurt in extended spring training and never got back, but I have to wonder how severe his injury really is. Unless he actually shattered a rib, I don't see how that kind of injury could keep him out this long.
I was pretty surprised to find that the guy had excellent numbers at Kane County last year, compiling a .905 OPS. He did strike out quite a bit (80 times in about 360 ABs), but he's young.
Considering who we passed up to get him in the 2003 draft, Daric Barton (heh), Eric Duncan, and Carlos Quentin to close out the first round, I'd like to see him do well and up his trade value (especially since it's looking increasingly unlikely that Brad Sullivan is ever going to do the same).