I have a few thoughts on Sweeney.
First off, he grates on me, he strikes me as a guy that always thinks he's the smartest guy in the room, and to be fair he might be but if he's that smart, he should know how to present himself better. Overall, I think he's okay as a GM; the 2015 draft will always be like someone that cheated on you; they might do 80% of things right after that, but there was that one time where they cheated. He'll never really live it down. But to say his draft record isn't good overall because of it is misstating the facts. And he does take swings at the deadline, they don't always work out (Rick Nash), but I still am happy he took that swing. All of us sit here and watch the 'game day' threads at the trade deadline, and we all want the big move, and it is nice to have a GM that makes some.
I thought he was more at fault than Cassidy this past year, but to be fair, I thought the Bruins should do a ton of things over the years that would have gotten me fired as a GM a dozen times over (and most of us here are the same). Cassidy has been a great regular season coach, but he hasn't been able to make the adjustments to apply that success in the playoffs, and I feel like we've had some teams that should have been better in the playoffs, so maybe that is on him.
Finally, Sweeney has got a lot to do over the summer, and he better be on the hot seat based on it. Try a new coach, try to fix the glaring holes in the roster, and see what happens. Next year, if we're right back in the same spot and Sweeney is back again, then the organization has bigger issues.