https://youtu.be/NgIiTumN0yw
Spending 5-10 minutes to foam roll at the beginning and end of a pitching session is important for short-term mobility during the pitching session. It also helps increase blood flow to the areas we will be using. PLUS, it just plain feels good most days...
It is great as a cool down post-pitching session as well.
The big areas a pitcher should focus on rolling pre/post-pitching is:
Spend 1-2 minutes on each area, per side. Over the long run, this be the most effective tool in an athlete's toolbox for recovery, injury prevention, and indirectly will increase pitching velocity (due to increased mobility that can be strengthened through exercise)