I just wonder if switching 1/3 of our defense is too much turnover. Not only because of chemistry on the ice, but these guys are pretty close off the ice. But we need to have someone on that 3rd pairing that can be trusted at 5-on-5 in most/all situations at the very least. I think Giordano would be ideal depending on what he costs.
I have zero problem with turning over 2 spots when the current group is unquestionably the team's glaring weakness. Their chemistry is not translating to on-ice performance and Parayko has had a rotating door of partners that he hasn't found on-ice chemistry with. Bortz is going to remain in the locker room and will likely still draw in to a number of playoff games if he is ousted from the everyday 6. He signed an extension that saw him take a 30% pay cut as a sub-$1M player. He knows his role in this organization and shouldn't be a problem in the room if he becomes a scratch. Mikkola and Scandella have combined for 189 career games with the Blues and neither were here on the Cup run that bonded half the team. None of us know the real dynamics of the locker room, but nothing suggests that those two are critical to the off-ice chemistry that keeps the guys close. I haven't seen anything to suggest that trading Scandella and scratching one of Mikkola/Bortz would destroy chemistry in a tangible way.
We're 5th in goals per game, 7th in 5 on 5 goals per 60, 6th in team SV%, 5th in team SV% at 5 on 5, 3rd in PP%, and 6th in PK%. Everything except team defense is good enough to be a genuine contender. But the 5 on 5 defensive numbers are ugly. 24th in shots against per 60 minutes of 5 on 5 play. 16th in shot attempts against per 60. 31st in scoring chances against per 60. 23rd in high danger chances against per 60. We're a bottom 10 team in the league defensively and we're very unlikely to improve that by shaking up the offensive group.
Adding 2 D instead of just 1 shouldn't be avoided over chemistry concerns. The well-known locker room guy in Bortz will still be in the room and I don't think moving/scratching Scandella/Mikkola is going to damage the locker room. Neither are leaders, neither have been here for a huge amount of time, and the guys in the room know that they aren't getting it done on the ice. If the team D just needed a slight improvement, I'd agree. But it needs to get much more than just slightly better.
Defensively, an improvement that leap frogs 10 teams still leaves us as one of the worst defensive teams among playoff teams. The group needs an overhaul. That could be accomplished with the right guy to partner with Parayko (and sliding Mikko/Scandella/Bortz down the depth chart) but it is more likely to be successful if you also add a second upgrade.