I'm not a mathematician so I'm not exactly sure how to analyze these charts as well as some, but I didn't see where it said he "bled high quality scoring chances". You inferred that because of the save percentage. Maybe I'm wrong. All I could see in the mathy parts was production and corsi impacts.
Am I just missing the scoring chance data?
I hate the trade. Think it was a stupid time to trade any player let alone one that has room to develop yet.
But, there was a piece some time last year that looked at quality of scoring chances against and Kassian was one of the worst if not the worst on the team for the forwards. I don't think that should be a shock though. He isn't very good at that aspect of his game and he needs to work on it. And because of that he will find himself in the doghouse. He cleaned up those things to get the praise he did and while he does drive possession he does have a habit of delivering a high quality scoring chances against. Some of that is that he doesn't seem to be able to recover when he does make a mistake.
With all that said, he is a guy to me that as you develop that part of his game you can exploit his offence by consistently pairing him with defensively responsible linemates instead of making him sink or swim on his own in that regard. Line matching would also help in that regard of course! And of course had they done this even if those aspects didn't improve he was going to return much more in a trade. 40-50 point players (and that is his pace) with his size aren't common.
To sum up...the issues with Kassian's game are very real. However, this coaching and management team have failed in ignoring the obvious chance to nurture his game and either develop themselves a nice player or a much nicer return.