I've had a lingering feeling that Soria has been a little "down" this season. Although his save/blown save and ERA numbers are fine, it has simply seemed, at times, that Soria hasn't quite been his usually dominant self. Is he? In short, no.
It's amazing that Soria saw his BABIP absolutely explode between 2008 and 2009, and we barely even noticed. When you strike out 11.72 batters per nine, you can get through that sort of thing. Although Soria hasn't quite maintained that level, he's made up for it by cutting his walks to a career-low level.
Over the last few seasons, Soria has started to give up harder contact, however. In 2010, he's also missed fewer bats. He's made up for those rises by continuing to strand a high rate of runners.
When you strike guys out, innings have a way of ending a little easier. I think there's more to be said here, but I'm not sure what. A quick glance at his Pitch F/X data suggests his velocity is basically the same. Perhaps his repertoire has changed, or there's a new scouting report out on him (as has been suggested about Greinke). In any case, he's been a little fortunate to not allow more runs, but not hugely so.