It is not just this season, he also played in allsvenskan last season and did that very well. He was one of the youngest in the draft with most upside and was one of the few that really have prove much at senior level, which give hime high floor as well. So he both had a high floor and high ceiling, in top 10 he should definatly have been pick in at the draft day.
People fall to much on hype from junior leagues. Look at how good the majority actually becomes at senior level. Players like Pastrnak are rare, and should be hold much higher in general among the jokes to scouts, that first looks at passport, second size, then passport again, then some down the line skills and what they have prove.