I wouldn't throw much at KCP. He isn't a bad player, but his time in Detroit was mostly about not living up to expectations and wildly inconsistent development. Sure he improved, but he never took that big leap he was expected to take.
As far as the trade goes, it's Detroit's win. You can't even spin this for Boston. Morris is okay, he has decent range and has shown a flash or two of being capable of more, but he isn't a great locker room guy and Bradley is clearly better and has more upside.
I like Hayward. Good behind the line, has a good midrange game, and plays decent enough D that he can at least hang with most 2s and 3s. He is never going to shut down a star, but Hayward has become very well rounded. Bradley was younger and more versatile and cheaper. I'm not saying they have made the team worse, but at this point their longest tenured player is Marcus Smart, a 2014 pick. They are going to have little chemistry at the start. It's entirely possible that by playoff time they start to gel and become a cohesive unit, but as it stands I don't buy them as a threat to the Cavs. To beat the Cavs, you need two big things. You need to play cohesive team basketball on both sides of the ball, and you need Cleveland to play a certain brand of ball. That brand is LBJ and Kyrie playing hero ball and ignoring everyone else on the team. The latter has happened a fair number of times but there are too many chips that need to fall into place for them to look like a threat.