Since McCarthy's repertoire is similar to Roy Halladay:
EDIT: since it might be hard to read, that's the location of all hard stuff (two-seam, four-seam and cutter) comparing McCarthy's 2014 with Halladay 2007-2011 (so before he went bad).
The issue with McCarthy is not that he's locating badly, but his cutter use is way down, as one user did point out. To be as successful as he was, the guy probably needs to regain his cutter from earlier seasons.
With his sinker getting more groundballs and more whiffs than in his Oakland days, I don't see any reason for McCarthy to keep having a 20% HR/FB rate. If his velocity and whiffs were down, sure, you would question xFIP/SIERA's usefulness. But McCarthy seems to still be good, possibly very good if his cutter comes back. And yes, I too have seen video of him getting hit hard.