Heres how I use MDP.
Make a list of all the guys I want to draft. If I 'like' the player I move them up 1 round, if I really like a player I move them up 2 and if I really like them AND they are trending up, I'll move them up 3 rounds.
This is a general rule and it depends on where in the draft you are. Early, I would move them up less and latter in the draft I might move them up even more rounds.
Also, remember you are trying to draft guys that will be ranked higher next year, not this year. So if you really think a guy is going to be great then by all means move them up even further.
But you can not concentrate solely on your team and completely ignore MDP. Even if you think Cruz will have a line of 110/40/115/25/.305 and win the MVP, it doesn't mean you draft him with the first overall pick. You'd miss out on another great player when theres a 99% chance you could still get Cruz several rounds later.
Hope that makes sense...