Yeah I don't get it, either. The above pairings are what have been working best over the last two years.
Dahlin spent most of his time with Jokiharju, but Jokiharju spent slightly more time with Power, and that pairing is just dogshit. Samuelsson-Dahlin also hasn't been great, but I think that could be deployment based; it's hard to parse out.
DJ/PS/BC give a pretty good mix of puck movement and passing on each pairing. The "downside" is that there isn't a stritctly defensive matchup pair. Buffalo doesn't have that sort of personnel so they should play defense via puck control imo.