The Flames look pretty full up on defence. In addition to the top three of Mark Giordano, T.J. Brodie, and Dougie Hamilton, there are also the expensive contracts of Dennis Wideman, Ladislav Smid, and Deryk Engelland. Throw in Jyrki Jokipakka, and that's seven guys already.
But that's not all. There's interest in bringing back Jakub Nakladal, so the Flames would have to make room for him. They also just qualified RFA Tyler Wotherspoon, who looks about ready to try out for regular NHL duty. That's nine guys in all, and not all of them can make it.
So exploring UFA defencemen probably isn't on the Flames' list of priorities.