So, I'm a big proponent of offense = effective defense.
That being said, I also feel there is a huge belief among hockey management groups that 50+ pt defenders are ones who need 7M+ and they are highly valuable and sought after (sup, Dion Phaneuf?).
I also believe that trying to score from the point regularly (a la Brent Burns, Shea Weber) is basically the NHL version of the long two-pointer in basketball: it is depressingly inefficient. On a team like the Leafs, that's taking the puck away from your actual firepower (Matthews, Nylander, Kadri), so they really only use the point shot for deliberate high tips, rebounds, and to keep goaltenders occasionally honest by bringing their shot down to the top of the circle.
What that means is, I'm looking for a 20-24 year old 3rd pairing defender that can skate out of trouble, make an accurate pass, and aggressively break up plays on a carrier, but who doesn't necessarily put up points. In stats terms, that means high relative CF%, low CA60, don't care about iCF but where the iFF is a higher proportion of the overall iCF (which means he can get shots through).
It also means I'm willing to ship out one of Rielly/Gardiner for a king's ransom because Dermott could make them surplus to needs for a fraction of the cost. I kind of want to keep Gardiner over Rielly too, because of the CA60 difference, but salary considerations and age might flip that around.