Supporting Performance can vary from movement to movement. For example your core throughout your swing is crucial to maximizing offensive efficiency. Likewise, an unsupported shoulder increases injury risk and reduces command. Either way, support is REQUIRED. The key component to supporting your performance lies within your core and how it MOVES and SYNCS with your upper half.
Although popularized baseball training (most of which is theory based) is mechanics driven, movement training is where support development is enhanced quickest.
SUPPORTING PERFORMANCE THROUGH DYNAMIC BALANCE
Since there are no "balance points" during athletic movement, supporting your swing or shoulder relies heavily upon a "counterbalancing" of body parts. Human movement is based upon counterbalancing and to ensure such is equal and opposite to force and acceleration, you must sync your lower and upper halves.
The "sync" is driven by a slow and steady acceleration to the point of contact or release. The quicker you move, the harder it is to support. Additionally, the back hip is where support lies, as all force is generated from such.
According to Newton's 3 Laws of Motion and energy dissipation principles, any imbalance or disproportionate energy flow will result in an equalizing reaction to compensate. In hitters, we see compensations in bent front knees, elongated swings, and premature rotation of hips. Pitchers are the same.
Dynamic balance is simple - equalize your acceleration to optimize your deceleration. If you have shorter movement planes for accel, you will see compensations in decel (and vice versa). The centerpoint, not balance point, to everything is your back hip and the longer it stays underneath your head, the more you support.