Bjornfot is just a classic example of a player who finished his development at a younger age than everyone else. I remember posting on this forum when he was 19 that he was going to be an excellent 2nd pairing defender, I (and I assume everyone else) thought he'd continue to improve, but he just never did, completely plateau'ed.
This was just a really bad draft by the Kings, but those do happen. The most disappointing thing about this draft was that all the top 2 round assets were allowed to depreciate down to basically nothing. The Kings should have been way more proactive in trying to move these guys before others found out, they were the ones who were watching all these guys everyday.