From what I read, Victor Rask put in a lot of work during the off season, and healed his ankle injury, but he is Exhibit A for KK making his line mates better.
That's a bit of the kind of offseason noise that you hear every offseason. He's mostly the same caliber player as when he was getting DNP's, but he probably did put in some level of work. He's actually recently been demoted to lower lines because he's an absolute anchor in terms of whiffing on shots, turning the puck over, not being able to win board battles, etc. He does occasionally flash some NHL level creativity though.
I mean you just have to look at Zuccarello last season compared to this season. If you actually watch Kaprizov on a game by game basis you'd realize how many grade A chances he creates for his line on a per game basis. If he had legit 1st line caliber linemates instead of a middle 6 winger and a borderline NHL level player, he'd have 15-20 more assists this season. He makes both of them better than they are, but that doesn't mean they are great (more focused on Rask).
Again, no hate on Robinson...he's a very legit and good player. He would not make Rask look like he was better than what Kaprizov is making him look like or has made him look like. Kaprizov is the reason that there is storylines like the one you mentioned regarding Rask.