I think it could be expected for a few pitchers but for the whole bullpen to struggle like it is right now is very suprising.
Yeah, and to struggle in the same way. That answer may fit for some of the babybacks, but not all. It's not like Koppy or Mantei were newbies last year. Randolph has always been this way - when on, he's great, but he walks a lot of guys. Choate was a cast-off and now we see why. Mantei always played with walks and HBP, he's had a delicate psyche -- and closers do implode.
Other possible factors: Injury-Oscar is hurt, likely from being grossly abused last year, thanks team. The more I've been reading about shoulder surgery, it takes at least a full year to be 100%, so give Koppy a partial pass - he is being overused, for being 9-10 months off surgery.
Inexperience Bruney has been a VERY top prospect, and he's almost ready to be up here, but obviously not quite. (Send him to Tucson to gain some polish. Get him away from this bullpen!) Daigle was upper-second-tier, and he's NOT ready to be up here - he belongs in Tucson. There is a Triple-AAA system for a reason- it's not only a holding pen.
Environment I don't think Webb or Valverde were exactly flukes last year, and being seen all season didn't hurt them then - they do not have control now like they did, and that has very little to do with opposing batters.
There's an axiom in my field that if something happens to one person over and over, it's in the person. If it happens to pretty much everyone, however, it's in the system/environment. GOT to look at the coaches, and the philosophy being ingrained (and maybe the guys who aren't here to influence younger pitchers and the guys who are) at some point, too.