The hips and glutes are the focal point of your running form. In essence, a lot of what is going on here is determining how the rest of the leg behaves. This means that the hips/glutes really determine a lot of how well your form is, your chances of getting injured, and your ability to perform.
This recent study suggests that the strength of the hip flexors can greatly diminish landing forces of the foot. More importantly, it suggests that having strong hip flexors can also replace the need for a person to try to switch to forefoot landing.
Now, before people start screaming through their computer at me, consider my thoughts on this. 1) Increasing the strength of the hip flexors will increase knee drive and knee flexion while running making a smaller lever (the swing leg) to have to cut through the air. 2) Increasing the knee drive and knee flexion will allow you to run faster because of the above. 3) Because of these things, a person is more likely to land, if not on the forefoot, at an angle where the braking forces are minimized, under the center of gravity, and with a slightly bent leg.
Of course, this is only one piece to a very confusing puzzle, but to me it shows a very important aspect to changing form that all people should recognize. That is, to improve form, you don’t necessarily need to be told what is wrong and that you need to change it. Rather, find out what is the underlying cause in order to fix the deficit or inbalance. If you do that, a lot of times you are well on your way to fixing the overall issues.