My theory is they didn't know what offers they might get for Phaneuf until they put him out there. When they heard the offers, they then realised it was beneficial for them to move him. I think when you have a guy with a partial NTC you probably don't hear many offers on that player, so they probably just didn't know what they could get for him.
Karlsson and Ceci and not a ton of proven guys after that would be rough, but they probably have targets in free agency. And I guess they have Chabot coming up soon, and maybe they were impressed by Claesson enough. They must just realise that if someone is offering them something surprisingly good for Phaneuf and they can get rid of that salary then it might help them.