Which Stewart signing?
I agree with you on this so far, but Sbisa does have potential. His decision making needs a lot of work, but Sbisa does skate fairly well and is willing to play physical. The talent is definitely there.
The market wasn't there for Lack. Comparable goalies such as Talbot and Niemi also received similar value. If you don't move Lack, then you risk losing him for nothing at season's end. Benning didn't want another goaltending controversy/sideshow to develop as we saw with Luongo/Schneider, and so he made the move.
Again - what type of return do you think an underachieving injury prone man-child with a questionable work ethic was going to fetch? Three different coaches had issues with Kassian for his unwillingness to compete and play defensive hockey when being used as a bottom 6 forward. Next season - Kassian was going to be an RFA and I highly doubt that him and Canuck management were going to agree on contractual terms.
If Benning/WD's goal is to foster an environment which is conducive to up-coming prospects, then Kassian absolutely had to go.
And Benning seems to be doing a great job so far. Virtanen, McCann, and Demko should all be key players at some point. As far as development goes, Utica went to the finals this year and our prospects definitely benefitted from that. Guys like Horvat, Baertschi, etc. will be surrounded by current/former elite players in the Sedins', Miller, and Hamhuis (if he counts), along with character guys (i.e. Prust, Hansen, Dorsett, etc.).