Stretching - for better or worse?

As it always crops up in runners' debate on how to fune tune their training, we'll sum up, simply but practically, the latest thinking as applied to athletics and, particularly, distance runing. A major compilation of research endorsed in 2004 by the  American College of Sports Medicine, concluded not very conclusively; -
- "There is insufficient evidence to endorse or discontinue routine stretching before or after exercise to prevent injury amongst competitive or recreatinal athletes." Anecdotally, from experience, the majority of coaches, athletes and physios would more likely recomend static stretching as part of a warm down at the end of a training session. This is when the body's raised temperature enables increased flexibility in the muscle tissues, ligaments and tendons. This , usefully, correlates with a 1990s study showing that marathoners who stretched after running were less prone to injuries than those who trained before, or who did not stretch at all. Amongst nations whose performance coaching advises against static stretching in the warm up, we can include the Eastern Europeans, Australia, UK and Spain.
The current best practice on the duration of stretches is along the lines of holding the stretch for about 15 - 20 secondsand doing two or at most three sets of each stretch on each side of the body. Given a sequence of maybe 6 to 8 stretches that, for distance runners, will bring in most of the main muscle groups needed to be kept flexible for running, some basic maths indicates why about 10 minutes is often the amount of time allocated for a purposeful, structured static stretching session.
As far as stretching's role in performance inprovement, looked at separately from injury prevention, we should think about the importance of maintaining the range of motion (ROM) needed for the specific activity. Each athlete brings a particular maximum ROM to any single training session or race. An 800 metre runner who wishes to improve from say 2.08 to 2.02 will, amongst other things, need to ensure an improved ROM is developed to enable them to run at this higher speed without incurring injury . Thus a sprint hurdler and a marathon runner will have very different needs and, in the main, the sprint hurdler will have a more extensive and demanding ROM across a wider range of muscle, joint and tendon groups, than the marathoner.  A distance runner needs to ensure that when they practice running at a particular speed, their warm up before running at this pace includes dynamic drills (ie drills carried out while moving)  to ensure that their 'functional flexibility' is maintained.  Even within the endurance spectrum, the dynamic warm up of an 800m runner will differ from that of a marathoner.