People saying not a steal, there is an element of risk to these contracts. They aren't signed with the intention of being a steal right away. Without a doubt, the Hurricanes probably could have shaved 2M off the cap hit by going for a bridge.
The cap goes up conservatively about 2M a season. Slavin is a UFA after 4 (?) more seasons of play? This contract buys up something like 3-4 UFA years.
How much does a UFA #1 D get paid under a cap approaching 85M? 7M? 8M? 9M?
Slavin is basically overpaid for two years (relative to what he could have been "forced" to sign for), and then will potentially be underpaid for 5 if he lives up to his billing. That's why it is seen as a steal.
Subban is the flip side of this. I am not saying Slavin and Subban are perfect comparables, but I am talking in the broad sense when it comes to young defensemen looking for contracts. MTL most likely could have locked down Subban at 6-8 years in the 6M range give or take, he would have been overpaid compared to the roughly 3Mx2 year bridge deal he signed for initially, but if he lived up to his potential (which he did) the contract would have eventually been a steal. Subban ended up signing 9M long term, so instead of getting a steal for 4-6 years depending on how long Subban would have signed for instead of a bridge, MTL only got a steal for 2 years during the bridge.
CAR probably could have gotten Slavin cheap for two years, but there is a good chance they'd end up paying him a lot more than 5.3M after those two years.