I have no real opinion on Johnson, I'd be happy if he works out well.
What I am interested in is where the talking point about how our defense/the way we play defense will better a player coming into our environment came from. I'd love for that to prove true, but am I mistaken in feeling our defense isn't exactly a strong point of the team? Despite quality overall stats during the cup runs, I feel the weakness of this team was undoubtedly the defense (and not just when compared to the offense with Crosby/Malkin), which was sheltered imo heavily by a combination of the forwards playing a 200-ft fore-checking style with superior speed than every opponent coupled with a hell of a lot of shot blocking (especially when Bonino was here).
They weren't exactly defensive stalwarts even during the peak of the 2016 buzzsaw, they were for the most part simply faster than everyone, which benefited puck-retrieval, blocking shooting lanes, pressuring puck carriers, etc. 2017 was a lot more reliant on shot-blocking and praying they wouldn't get scored on, while relying on rope-a-dope odd-man rushes off turnovers for scoring because they weren't as fast and thus dominant possession-wise. At least based on my memory of events.
So yeah one can point to Schultz as a reclamation project that worked out, but I'm not seeing or at least would welcome someone convincing me of the promise in the defense as a whole going forward. Said potential promise being based on expected adjustments to what failed them in 2018 I assume? I was under the impression poor defensive coverage along with the inability to adjust away from continued failed pinches leading to odd-man rushes (what gave them issues against Tampa Bay in 16, and ironically what we did to the opposition in 17) was the primary reason they were eliminated, along with a lack of secondary scoring and Murray struggling being prime causes as well. The way some in the media have covered this signing you'd think we were the Kings defensively or something.
Johnson can come in and exceed expectations all he wants if he's capable which would be great, but I'm not yet sold on the unit as whole let alone it's individual parts. If someone can convince me otherwise I'd love to hear it, it's my only real hesitancy going into next season and would appreciate some optimism if it's warranted in this regard.