Yeah, sometimes top 5 picks don't pan out. In fact, most of them don't pan out according to the Best Possible Player Projection Comparison (which is stupid anyways). Comparing him to other picks from the same draft, because of what they have accomplished is also downright criminal. None of them have played more than 85 games and (hopefully) have more than 10 seasons ahead of them in the league. The amount of "show me now!" in this thread is ridiculous - the kid stepped into the league at least a year ahead of 95% of all d-men and was just fine. What the hell else do you want? Put up 90 points and fondle you at the same time?
As for "you can't improve your skating" is a bunch of horsesh!t. Kid is barely 20 and has plenty of time to fill out his frame and adjust his body. Or maybe you're so naive that you think it's some random deity that grants a player with skills and he can't do anything to change? Ask Gary Roberts about that. If Larsson wants to, he can improve his skating, explosiveness and stride. Even if he doesn't, he's virtually a lock for being a top 4 defenseman with his vision and first pass.