Goaltending is playing a role, but this is a team that also had Ullmark and Lehner and discarded both as unworkable.
Lehner blossomed in Vegas and Ullmark is dominant in Boston.
So, yeah, an upgrade from Anderson and Comrie is needed, but not so sure about dumping UPL after half a season. He's already 20th on the all time Sabres wins list.
Team defense is key, as we've seen that Ullmark isn't quite so dominant when he's not behind a team like Boston. He's not the only reason they're the stingiest team in hockey.
That said, if there's a solid starter to be had - by all means go get him.