The value of staying the extra years in Sweden is becoming more offensively skilled. Too many Swedes can over too soon thinking they could make an NHL roster by learning to play the North American style game, struggled and ended up being a bottom 6 AHL player and not developing offensively. So they never made it to the NHL since they lacked offensive skill and were beaten out by North American players better suited for bottom 6 roles.
The same thing that happened to Sedlak ruins a lot of players' careers - they're told they need to learn to play better in their own zone, hit more, etc and they don't remember the whole point of the game is to score and that's all they focus on. Sedlak said it was a revelation to him that he should go onto the ice and actually try to score a goal rather than try to stop the other team from scoring. If that hadn't happened, Sedlak would be back in the Czech Republic now.
The same thing easily could have happened to Stenlund if he came over last year and was a bottom 6 player for the Monsters and told he needs to get better defensively to get a call-up. Instead, he stayed in Sweden and focused on offensive skills. He still needs to get better defensively, but at least his offensive skills might get him a Top 6 spot now.