Yeah, I can't wait until the season starts and the fans start to see this; they will go through these stages:
1) Larsson is still getting adjusted to the coaching system
2) Larsson is not used to the pairing; he's pairing has no chemistry
3) Larsson's coach is not using him correctly
4) Larsson is being overexposed, playing too man minutes
5) Larsson is only 23
Given the gamble that it was, in the sense he isn't a bonafide #1 yet and may never be, but should be a quality 2-3 shutdown D who can move the puck and play big minutes, those are perfectly reasonable explanations.
I fully expect it to take at least 20 games for him to get comfortable (at least), it's not even certain who his D partner is going to be although one would expect it to be Klefbom, which could help accelerate the adjustment period if they end up meshing well together. In terms of coaching, I doubt that to really be a problem but if he doesn't get a sniff of the first unit PP that will be on coaching, most notably the PP coach Jay Woodcroft who was a ****ing train wreck last year.
If injuries hit early and he's one of their healthy guys, I can easily see him being played too much, because ultimately this has been the case the past 5+ years, guys playing in spots way over their heads, because of injuries and lack of quality players.
And it's true, he is only 23. Unless he gets slaughtered, I hold out judgment on the player until after the season is over.
Quite honestly I don't expect it to be too much of a problem though. I think the Klef-Larsson pairing could be big time IF Klef can stay healthy. Big ask, but I think it can be done. Be nice for them to add Tyson Barrie though.