With Halladay as the only major SP target out there (outside of Lee) there wasn't a whole lot to fall back on unless you wanted to take a chance on an injured Peavy or Washburn. I know you'd make the trade but Buchholz/Bard+ price was way too steep and I don't no how you can't question that if you've watched the past two weeks of baseball.
As for SS, the organization has faith in Lowrie and for good reason. He hit .258/.339/.400/.739 last year in his rookie year and has been fairly highly regarded as a prospects. I don't think the FO is going to let 23 AB since his return affect any judgment on his playing ability.
And OF, there is no Dave Roberts out there. They acquired necessary depth guys in case something happens and I don't think you can ask for much more.