He made $6 million in 2012 for... doing nothing. Soria had Tommy John surgery and missed the entire season. He had contract options for $8 million in 2013 and $8.75 million in 2014, with a $750,000 buyout for each option. Which is why this should come as no surprise:
#Royals decline 2013 club option on reliever Joakim Soria. Soria, who missed all of 2012 following Tommy John surgery, is now a free agent.— Kansas City Royals (@Royals) October 31, 2012
Soria, who is 28, could still come back and have productive seasons. The Royals might even bring him back at a lower price, but it's totally understandable why they didn't want to pay him another $8 million not knowing whether he'll be ready for 2013.
He might also be an attractive chance for another team who's looking for a closer, or even to have him set up.