Moving Lehman to MLB is like moving Redding to DT so you can draft DE. I don't think either player was effective playing those postions and have started to settle into their current postions.
When it comes to the draft the only question you need to ask is if the player is signifcantly better than the current player. If he is can the current player be cut, traded, moved or made a backup.
If not don't expect the Lions to draft that player no matter how good he is because of the salary cap.
I think you contradicted yourself...
You said that Movng Lehman wouldn't be a great move, but then later said that moving him to draft a better player (like Johnson would be), is fine.
Johnson is a much better player than Lehman... drafting him would be an upgrade over either OLB on our roster.
Alas... Johnson won't be avaliable at #10. So it's really not a discussion.