The fact that some people from other fanbases are going out of their way to try and take the wind out of the sails of this pick speaks volumes as to how good of a pick it actually was. There are a number of factors (mono, injury, coming back to soon from mono, not playing WJC, getting bounced around) that contributed to his season, but you don't just lose god given ability. He is arguably the best skater in the draft, good shot, and offensive decision making.
This whole nonsense about low hockey IQ is garbage. If anything he was forcing plays because he was trying to do too much, which is evident based on the fact that his hockey sense was not perceived as an issue prior to the mono. The same stat watching scouts on the site tore down Chychrun last year saying he had a low hockey IQ, which was garbage as well, and low and behold he made the NHL this past season and is most likely going to be the top D from that draft.
The other factor I believe that cooled some of the hype surrounding Liljegren was the emergence of Dahlin. Suddenly another sublime Swedish D emerges just as Liljegren gets mono, and scouts start drooling over the shiny new toy. I am glad the Leafs management sees beyond Liljegren's misfortune this year, looked at "his full body of work," as Mark Hunter put it, and drafted arguably a top 3 talent at #17.
To me the Leafs just drafted the missing cornerstone in the rebuild, the one I didn't think they would get, because of how fast the have risen up the standings. Liljegren under Babcock (and in his system), and pushing the puck up the ice to Matthews, Marner and Nylander is going to be scary.
Similar to Chychrun last year there is going to be a lot of crow to go around for those trying to tear down this kid, and a lot of teams and fanbases that are going to wish they didn't pass on him.