DMI isn't a great way to compare to different players... DMI is a reflection of a lot of things that can easily askew who is the better player. Examples being game shape, if a player has received training when another has not, etc.)
It's better to compare the stats of the players and move from there. If their positional stats are equal, look at whoever has better intangible stats, or who will fit in your plans for the long term... Age, Height, Salary...