Could be the case that the Hendricks injury is extra bad, but several young players have come back from a major injury better than they were before. For example, there are a lot of "rookies" who missed their first season but came back a better player because they were able to improve their mind/other physical traits while sitting out. You can't work on everything while injured, of course, but the process of learning to be a professional/adult can happen while on the sidelines.
We don't really know what Hendricks was if he didn't get injured, but I could see him being much improved from his rookie season.