He had short periods where he played a bigger role on a very bad Ottawa team, but he was never able to stick with it. He rarely rised up as more than a 6-7 tweener type outside of his one big season. Outside of one season, he was never a #5 D here.
Look at our D core over the last 5 or so years and consider that Brannstrom failed to stick there over multiple coaches, and then failed to make the Avalanche.
People are gushing over him in VAN while he is playing incredibly curated minutes. If he takes another step forward that's one thing, but as of now he has shown nothing to suggest he will stick in the NHL as anything more than a guy they can plug in when needed if they manage his deployment.