If you're weighing the odds of a 2nd rounder being better than Zuccarello then you're looking at it from entirely the wrong perspective. The rebuild is about the big picture and what you hope to come out with in the end. It's not about trading X and making sure that Y+Z >= X.
Of the top 50 scorers in the league right now only 12 are playing for teams other than the ones they were drafted by. 3 of those 12 were FA signings: Panarin, Tavares, and Wheeler. Some of those guys like Skinner, Lindholm, and someone named Zibanejad were floundering with their old team and wound up being shrewd moves for the new franchises.
The cold reality is that most of the elite talent in this league is drafted and held onto for dear life. So the more chances you have in the draft the better your odds are of finding those players. I can understand people have some issues with our drafting over the years and that's fine, but there aren't really any other viable options.