When the Lions traded for WR Dennis Northcutt, it meant the immediate departure of one player (safety Gerald Alexander) and it might mean the eventual departure of another (WR Ronald Curry).
Northcutt was dealt to the Jaguars in a one-on-one deal involving Alexander.
Northcutt should have an impact on Curry because now both players are vying for the slot WR position.
Northcutt has been productive throughout his nine-year career and also gives the Lions a presence at punt returner. Curry, who was signed as an unrestricted free agent, hasn't shown much so far in the off-season workouts and there are concerns that his speed has diminished.
While Alexander was expendable, it's unlikely the Lions would've picked up Northcutt if they had been happy so far with Curry.