Honestly, I don't think our defensive play has been much worse than last year. We just didn't get the goaltending early to where we could find any traction. Last year Cory was good until late December and we were able to get enough points to withstand bad (Cory) or inconsistent (Kinkaid) goaltending for about 5-6 weeks until Keith caught fire.
This year we just never really got going. We started 4-0, then promptly dropped 9 of our next 11. Kinkaid was actually around league average through November, then the wheels came off him completely. I certainly don't think it was all just goaltending, but given that Cory and Blackwood are both playing better behind a worse roster leads me to believe goaltending was a pretty significant factor in how this season played out.
To be fair to Kinkaid, he's a career backup who got hot for 6 weeks last year, so expecting him to repeat it was probably unfair. Still, his numbers from December on were staggeringly awful and well below even his career averages. It seems like things just snowballed on him, like it did for the team as a whole.