So, I watched the Blackhawks/Red Wings game today. NHL Network used the Fox Sports Detroit feed, with Ken Daniels and Mickey Redmond calling the game. On every questionable play- and by "questionable" I mean "only the most delusional of Blackhawks partisans would have any problem with it"- they fell over each other to excuse the Red Wings of any misconduct.
The role of the home-town broadcasters is hard to pin down, I suppose. They almost certainly get close to the team, and their primary audience is the team's die hard fans, so there's a lot of incentive for them to give the team some rhetorical support. If they knew they were going to call the game for a national network (and NHL Network counts for that, more or less), then there's the added impulse to kind of help put the team's best foot forward.
But still, the primary job of the broadcasters is to inform the people watching, and to do so accurately and fully. The impulse to support the team on the air, that's actually what makes the job hard enough that they don't give it to just anyone. You gotta put that aside when the team is clearly on the wrong end of things.
Now, I don't know if the Red Wings were committing penalties that went uncalled today. I don't know how the game is called quite that well. But it's a tough, physical game with a lot of gray areas, so I'm sure that the Wings weren't just as pure as driven snow for all 60 minutes. And their broadcasters' job was to tell us that, even if their sympathies pushed against that.