Problem is, that’s a third pairing on a team that has sights on contending.
Any combination of Myers/Soucy/Cole/Bear/whatever as a second pairing is simply not good enough.
I think you can have #5's/borderline #4s in your middle pairing as long as you have a dominant 1st pairing. They definitely need more D-depth, that's for sure, but Soucy and Cole can handle pretty decent secondary minutes.
Ideally, a genuine top 4 D is brought in to pair with Soucy, and Cole/Zadorov can anchor the 3rd pairing.
Team needs a second pair the coaching staff can lean on to be steady defensively. Can't have that with Juulsen or Myers effectively guaranteed to be there, bringing down their partners.