Boston had everyone playing according to personal responsibility. What they managed to do extremely well was clog things up as a team. And they had the personnel to do just that. Which meant that weak or strong defenders alike could focus on their personal responsibility, as well as looking to stopping the ball even if it means leaving their man. The key in my eyes is realizing the point of commitment in terms of help. There has to be a good balance between defending the ball and your man. Help too much or too soon and you're just allowing your guy to go off. Stay too close to your man constantly and you're letting down your team on penetration.
Boston held down the paint very well, with everyone sticking a toe in there at once quite often, and then being ready to rotate out to the perimeter on the pass, or collapse further on penetration. And you know what? They gave up a ton of shots. They allowed the Lakers to make some big comebacks, when the shots were falling. They ultimately did very much of the same things the Raptors
did. The Raptors
did a good job of making teams settle for shots from third options, by working well as a team. What absolutely killed them on defense happened almost exclusively early in the shot clock, and you need look not much further than Jose who just offered zero initial resistance to ballhandlers in transition, while the bigs were just too soft and unable to work together to close things down in a hurry on those occasions. Guys like AP would then have to commit to helping way too early, and things would look ugly from there. And that allowed opposing teams to play comfortably whether they were hitting shots or not.
Hell - look at Boston in the playoffs some more and you'll see they also had some of the same problems on the road. When the Raps faced anything but early offense they proved to be very much improved. Now with a specialist like JO in tow, that whole point of commitment thing can really pay off much better. And Jose needs to be able to show that he can actually channel players into a swarm instead of waving his arms from behind his man like I saw him do against Jameer Nelson of all people, after Jameer just went by him and stuck Jose on his backside. At least he had the behind the back pass covered. You can't just make a small attempt to steer a guy one way or another and be done. You still have to be active in stopping the ball. Jose simply couldn't handle any kind of speed. Really - I can't see how Mitchell was going to mask that kind of imbalance off of transition. Could that maybe be why he's so happy about bringing in JO? JO could change everything exactly by allowing for weaknesses to be masked.