Forgive me if I don't just trust the tooltip. They are usually the last to be updated correctly.
Especially since everything I read about initial theorycrafting from beta said it works like the other smart heals. For instance,
https://healiocentric.wordpress.com/...and-high-tide/ says:
"Well, what is up with that is that smart heal technology is changing, so smart heals will no longer flock to the most injured player in the raid, but will choose randomly amongst them."
I looked through my logs and I couldn't find a good way to show the current health of all raid members when chain heal is cast. Pls to provide such proof.