What I see with regards to Dillon / Schultz / TvR:
The Dillon Shultz pairing seems to require Dillon to be the defensive D and Schultz to play up and create offence. This puts pressure on Dillon and he rushes his plays and turns the puck over or makes a bad pass.
The Dillon TvR pairing takes that pressure off Dillon because TvR is (imho) a very good defensive D. This allows Dillon to play further up ice. He doesn't really generate offence (even when he tries to), but I think the key factor is that he
doesn't have that pressure on him because TvR is back there covering.
I also noticed that in the last two or three games that TvR played he was playing up ice more often. Much like Dillon he isn't a guy I expect to create much offence at all, but I found it notable because previously he would always stay back in the D zone.
As somebody else pointed out, TvR has a very good long pass.
It's a tricky situation because these three guys are all different types of defencemen so they aren't interchangeable. On a lot of others teams I would expect all 3 of them to be mainstays in the lineup.
Anyway, those are my observations (rightly or wrongly)