One of the many studies out there (google mofu) was done th ethe military and it showed that static stretches done as part of the warm up did NOT help increase the range of motion and even hampered the ability to produce strength.
Warm ups are just that, exercises that warm up the core body temperature.
Statics are best done as part of your cool down or a separate session like Mr Punch mentions after you warm up though.
Its pretty much "common knowledge" nowadays that warm ups should be moderate paced aerobic activities like calesthietics and dynamic stretches that start with limited range of motion and work their way to full range.
Psalms 144:1
Praise be my Lord my Rock,
He trains my hands for war, my fingers for battle !