The article I cited previously,
pointed out downsides to college players coming out of college and burning a year. Basically it said that if a player still needs development, the team is less likely to invest in that development if they have less time to develop him, and cited a few examples of college players who never were able to make the transition to the NHL. (If Johnson was 22 already this would be more of a concern because players who sign at 22 only get 2 years on their ELC, not three. Burn the first year and they go RFA after a year; if the team still isn't sure what they've got they're less likely to give them that second contract.)