I do dynamic work to warm up before a hard session or race... whether that be strides/sprints, gradually increasing in intensity, or perhaps even a few drills.
Still a fan of static stretching after a session... although strangely i do a routine of stretching after every easy run, but usually forego it after a race/hard run, as too tired to stretch properly.
The principal of dynamic work before exercise, and static work after, is one i have seen throughout my kickboxing days and within my running club, so it is clearly popular (of course that doesn't mean it's necessarily correct... seems to be contradictory "evidence" for everything nowadays)