There are lots of intangibles that make defencemen really good to have on your team and are important to playing defence.
Hitting, and being able to take hits and not cough the puck up, moving players out of the front of the net, not giving opposing players second chance opportunities, creating fear in opposing players, fighting, being nasty to play against, blocking shots which is hugely important in playoff hockey etc....
These are just a list of a few of the intangibles. There are many more that could be added to my list.
There are defencemen that are not on the list of top 50 NHL defencemen that bring a lot of important intangibles that are needed to develop a successful defence core on any team.