I think fans concern themselves with "a down year" lowering players' value way more than organizations do. NHL teams have lots of pro scouts. They know who a player is year-over-year, they know his style, they consider the context of a poor season, team quality, coaching, injuries, all that. It's not like GMs are on the phone like "Oh, you're offering Gostisbehere? Hold on, let me pull up HockeyDB real quick."
Certainly, a down season will call into question a player's long-term consistency, which is an inherent part of his value. But Ghost turning around and potting 55 points next year isn't going to change peoples' perception of him too much either. He's 26, he's had two 60+ point pace years and two full seasons where he was stuck in the 30's. Teams kinda know what he brings.