Dickey looked really good this year for most of the season, is guaranteed to eat innings, and is set to make only 12M for 2015 and 2016 (club option with cheap buyout). I think lots of teams would be interested in that. Including many NL teams.
Buerhle is no better in terms of.pitching performance, and costs 7M more for one season, then could be extended or qualified.
As dependable as Buerhle is, Dickey is a better value.