You have a point there but the reason I mentioned 2014-15 was because Larsson was still in the dog house (DeBoer) and their D wasn't much better aside from the fact Greene was younger.
Greene was dominant that year.
He was playing like a #1 D and the team was playing a system under DeBoer that controlled possession and negated a lot of high scoring chances.
This year's team has massive liabilities. Greene is half the defender he once was, Quincey has cinderblocks for skates, Lovejoy is a solid 4/5 who needs a puck-mover to carry him on a second pairing, Auvitu is a new French transplant who hasn't learned to win a board battle at the NHL level, Moore is all tools and no toolbox, and Merrill hasn't shown to be an NHL caliber defender since a brief stretch his rookie year.
Combine all that with the fact that they are one of the softest defenses in the league and we just get walked around with ease every night. The forwards don't help much defensively either.