I think people need to realize that most GM decisions aren't made by just the GM, unless you believe that Philly story about Hextall going rogue and selecting Patrick is a common practice. GMs can't go around and watch every single player on every single team, so they have to rely on their assistant GMs and scouts to give them accurate scouting reports. These kind of decisions are never just made by the GM. What does that mean? There was more than 1 person who wanted the Penguins to acquire Granlund.
It's the same thing as when Toronto traded for Matt Murray last off-season. That wasn't just Dubas saying "lol he's from my junior team, so I'm trading for him". That move had to get approved by Shanahan, who seems like a major meddler with the Leafs, and had to get insight from their scouts on what they thought of Murray. Another example was when JR traded Despres for Lovejoy, do you think that was just JR or do you think there were more people there (such as Guerin, who was rumored to be a big supporter of that deal) who supported that deal?
A GM has the final say for the most part, but I'd bet it is extremely rare for a GM to make a trade without the consent of his supporting cast. And following that, I'd bet that it's extremely rare that the only people who would support acquiring a player were only on 1 team.