Consider that "Form" is also weighted heavily in the DMI. Looking at your roster page, it seems that the guy who has DMI of 25300 has Proficient form. That's probably the largest contributor.
Also, the avg rating is only low because of the one game where he happened to suck, and got a 1.0. That rating focuses heavily on shooting, and this guy seems wicked good with assists instead, so you might consider this as well.
Also, keep in mind that the DMI is intended to be somewhat meaningless, and fluctuates quite a bit.