Also, simple resource allocation.
If the team decides it doesn't want any of the three RD playing on his off side (an eminently reasonable position), it's poor asset allocation to have three A+ guys who can only total 60-65 minutes (counting PP time), while simultaneously playing three C+ guys another 55-60 minutes on the left.
Much better to play 2 of the three a total of ~50 minutes (especially with Lundkvist looking ready to step in and take the remaining time) and devote the third to acquiring a guy who can go play ~25 on the left, who can upgrade that overall contingent to something in the B to B+ range (and hopefully improve from there as the kids come up).