Odds: As it stands now, I say there is a greater chance that the Lions will draft Johnson than there is that they will trade the second pick. There are two reasons for that prediction. First, the Raiders might draft Johnson, which would diminish the value of the second pick. Second, if Johnson is on the board, it will be very hard for the Lions to pass on him.
The draft cannot be driven by mistakes of the past. It's about what helps a team now.