I am going to try to clarify my stance so people maybe stop the strawman-ing. Let's break things down into 3 distinct parts.
1) Blues trade for and sign Faulk as a pre-emptive move
2) Blues Sign Krug
3) Blues lose Pietrangelo.
Any 2 of those does not sink us. Sure people might be upset at any of them, but not this upset. It's the combination of all 3 that sink us. Without Pietrangelo, we don't have the horses to cover those 2 guys. We cannot have them both on our team. The contract lengths and amount make it difficult for us to go out in the future and somehow get a better Pietrangelo replacement. The two sheltered big name D leave little room for us to groom our younger players who are similar (Dunn and Perunovich).
If we signed Faulk and lost Pie, we could wait and try to find a better fit with the money we offered Pietrangelo. Maybe make a run at Hamilton next year if he pops free or trade for someone.
If we signed Krug and lost Pie with not Faulk, same thing.
If we had all 3, I'm not sure how cap works but at least we have the horses to cover those guys. We move Dunn. Have Parayko-Scandella be the shut down pair, with Pietrangelo helping cover Krug and Faulk sheltered on the 3rd line.
As we are, we have no viable pairings that doesn't leave a sub-standard defensive player exposed against good competition regularly. This will not change for 7 years.