Good question. Let's assume that everyone is correct and cap space is the new hot commodity over everything else. In that case, teams spend and move contracts to get to the floor and teams move out contracts to free up cap space.
Today, NHL teams filled a ton of space that Backes could have been moved into. Toronto pounced on Ottawa's cap space.
So my concern with Backes is twofold:
1. Backes decides that if something isn't done before the summer he will not waive.
2. No team has cap space to take him on in August or September.
Holding onto him and all the hundred or so 4th liners and bakers dozen of D protects them from injuries but ensures that the cap is spent on the current lineup and not fixing the HOLE.
I don't LIKE the idea of holding onto him. I hated that signing and was the constant basher of it from day one. But the word is out...he stinks! The Bruins will have to pay dearly to get someone to eat him, and clearly they don't feel the sense of urgency to do so or, as you note, they'd have paid up to do it with some of these teams that have space.
End of the day I see him back here, sitting in the press box and/or playing in the A and collecting his check. They don't owe him NHL games and Cassidy has shown he'll sit him when he wants. So we're left to hope Sweeney feels urgency to add talent and thus free up his money, but if I was GM who just went as far as one team can without winning, not sure I'd feel all that much urgency.