Quoting: KakkoForMauriceRichardAward
It's easier to be good at offense than being good at defense. Plus you have twice as much forwards as you have defenders, which makes d-men VERY valuable. See how Matheson, JJ (arghhhh) and Ceci got new contracts even if their last 2 seasons were pretty terrible?
I disagree with that first sentence 100% especially at the NHL level.
You can teach young players how to play defense, you cannot teach them offense. They either have those offense instincs or they don't.
Drew Doughty is a perfect example. He was more noted for being an offensive defenseman as a prospect, although his defense was underrated, it was not the most notebale aspect of his game. In his first NHL season he was horrible defensively. All offense, no defense. In the following off-season and during the next season he worked at his defense game and really excelled and soon became known as the most complete defenseman of his generation.
There are many more examples, but that's the best one I can think of.
The Kings have a better chance at developing Tobias Bjornfot into an elite shut down defenseman than they do making him a 50 point dman. Not sure why I picked Bjornfot, but I did lol.