The DMR basically takes four relay legs and gives them different levels of importance. The middle two legs only run 30% of the race. The 400 and 800 legs never really make an impact when there's a strong field. It turns into a 1600m with the starts offset by the differences in the 1200 legs, and even that isn't a whole lot compared to the 1600.
When you're the anchor on a 4x4 or 4x8 or 4x16, you're doing your part just the same as the three legs before you. When you're the anchor on a DMR, you're doing more work than anybody else and yet your whole team gets the credit for your finish. You gotta think that the DMR was created by a frustrated high school coach who had 2 or 3 stud mid-distance runners, but not enough to field a great 4x8.
I hate the DMR.