While I'm also unhappy with substituting Bart in, this is what I believe to be the reasoning behind it.
The Blue Jackets are the size and skill deal, creating chances off the cycle and through an aggressive, physical forecheck.
But one thing of note is that they are hurting very, very badly for scoring now. Like, imagine if Monahan and Gaudreau were on 50pt paces, that's how bad it is. They've attempted to replace offense lost through Hartnell / Saad with Panarin, but they're very aware they won't be able to score goals the way our team does with speed, vision and skill. Furthermore, they are in a division where they're often facing stalwarts between the pipes:
- Schneider
- Murray
- Holtby
- Lundqvist
Furthermore, sprinkled throughout the rest of their conference:
- Price (I know he's in a downturn but still)
- Vasilevskiy
- Rask
- Luongo
And on top of all that, their snipers have gone cold. So without all this scoring prowess and having to face a murderer's row of goaltending in their division, how does one create offence? You do it the meat-and-potatoes way. Stapling someone's butt in front of the goalie at all times. Beat the other team up on the boards with your size, force mistakes, and create mucky chances on net.
Having Smith be on his A-game isn't going to faze them one bit when they're facing potential Vezina challengers in net practically every game. The Jackets will have someone parked in front of him, I would bet on it. And be throwing hits all game.
That's where Bart comes in. The Flames need their defencemen to turn into the surliest grumps possible if that happens, and Bart loves physicality. He will throw himself into the fray even though he's more slight. And while he handles the puck like it's a cinderblock, at least he can skate well enough to not be wildly out of position... I hope.