IMO you have to let an offensive defenseman like DeAngelo make some mistakes. The only offensive defensemen who don't make mistakes are elite level franchise guys and actually they STILL make mistakes. You gotta let him grow and learn how to find the right balance and then maybe if he's still not balancing out mistakes made with positive points etc, you cut bait and realize it's not gong to work out.
It's just...you can't develop an offensive defenseman by insisting they play mistake free defense at all times.
Trying to level out those guys almost never works.
You end up staaling their offensive development while bringing their defense up to maybe acceptable. The player goes from someone who does one thing well to a player who does nothing well.
Let him play his game, he'll do much more good than bad.