Each year across the NFL, there are teams that make surprise selections in the NFL draft. The selections of players comes with the possibility of happiness among players, but also comes with the risk of players being unhappy.
When a team ends the draft without drafting players at a specific position, that is going to make those players feel confident heading into the season.
It is also possible that the morale of a player is going to differ based not on whether or not a team drafted his potential replacement, but rather at what point in the draft was that player taken.