They're BAD depth payers.
This organization doesn't acquire good players. They inherited all their good players and only sign BAD depth grinders to play BAD grinding, 4th line hockey.
Focus on the core you say? Which core players did BargainBin add in the last four fkn years??
Again that's the thing you don't seem to understand, good or bad, depth players are not part of the big picture. It doesn't matter if a depth player is good, average or bad, all these players are not part of the big picture which is bringing the cup back. And btw bad is your personal opinion, as an emotional fan seeing your team missing the playoff you say: "everyone is bad!!!"
What happened? The Habs finished 2nd in 12-13, they had 100 pts+ seasons after, they made some playoffs rounds, all the young kids are improving, Therrien was a Jack Adams candidate at the start of the season, and all of sudden every player, the GM, Therrien, everyone is bad?
Calm down, don't be too emotional. This team has a good core and the GM has a good plan and is not emotional contrary to you.
Regarding your last part, Bergevin doesn't necessarly need to the add to the core, he said since the beginning that the core will be built whithin the organisation, through draft picks, that means, Galchenyuk, Gallagher, McCarron, Scherback, etc this is how Bergevin wants to build his core. If you don't agree with his method, fine, but you have to realize one thing, every contender in the league right now are built the way Bergevon wants to build his team.
To answer your question Bergevin added Petry as a core player, we'll see in the future if that was good move, we can't judge yet.