The purpose of stretching is to be able to move without “tightness”. If the athlete has assimilated the training instead of being annihilated by it, often the tightness or soreness will be minimal.
The other consideration tied up with this is Massage. I know it’s expensive and I didn’t like to do it, thereby avoiding even the possibility of weirdness if any of my athletes were crazy.
But with some solid massage, hitting trigger points etc, the need for stretching of any kind during the warmup was largely reduced if not virtually eliminated.
ESTI, Duxx, others: I would be very interested to know if there is any research (a brief abstract would suffice:D) on the implications of hydration and heat on flexibility.
We all have been there on those real hot summer days when the warmup takes considerably less than normal, so heat seems to be a huge player in the loosening, mobilising process - hence perhaps the success of the “continuous warmup” which heats you up internally as it were.