DOWN TO THE CORE
Let's take a look at how the core can help out when throwing the football. First, understand the importance of what exactly is needed for efficient and powerful throwing. Both the inner core and the outer-core need to be strong.
For quarterbacks (and most rotational athletes) core stabilization and strength is a must. To generate the proper max. rotational velocity when throwing the football, the core has to be initiated and sling/twist tension must be created. If the inner core is not engaged then the outer-core lacks the ability to perform, therefore leading to non-existent stability and ultimately a weaker throw. Think in terms of a house, the structure will not be very secure if the foundation is not strong. The foundation, in this case, is the core. "Strong core allows you to throw more."
Begin working in some of these core exercises into your workout:
-Band-resisted bird dogs
-Planks (with a Bosu ball or stability ball)
-Medicine ball rotational throws
These exercises will fire up the TVA, obliques, rectus abdominis and pelvic floor muscles in the core which will help you get that juice into the throw (also helps with lower back pain). If you don't know any of these exercises, simply type them into google or youtube and there will be a number of examples!