If I'm reading it correctly, I think a more accurate way to phrase that would be that his strengths come into play most often when there is sustained DZone time. That's not quite the same thing as him being at his best.
While size isn't the be all and end all, the Flyers lack size on defense, and Friedman disappointed me in that he's not as strong as I'd hoped (when Marchand can flip you, well . . .), Ghost is obvious, Sanheim plays smaller than his size in the D-zone, Gus is still trying to master defense 101. Basically right now it's Provorov, Braun and Hagg until Myers comes back.
If you move out Braun and Hagg you easily have the smallest defense in the NHL.
Does that matter? I've been told Cooper is a genius, and TB has the largest defense in the NHL, an accident?
So as a HC it's a bit of a dilemma, I can play the more skilled defensemen and know that teams are going to emphasize a physical forecheck and try to wear them down and send players to the net with impunity. Or I can play the slugs and know I'm lowering my skill level.
It's going to be worse with Zamula, though maybe York is the mighty mite I was hoping Friedman would be (shorter player with strength who knows how to use leverage to compensate for lack of size). Millman, Andrae, only Attard and St Ivany (and Ginning if he ever learns how to play hockey) have size, but both are probably 3rd pair at best.