The core is a structure within the body that consists of three layers of muscle:

Deep Muscle Layer: Position sense muscles
·         Rotatores
·         Intertransversarii
·         Interspinalis      

Middle Muscle Layer: Inner Unit
·         transversus abdominis (TVA)
·         internal obliques
·         lumbar multifidus
·         diaphragm
·         pelvic floor3.      

Outer Muscle Layer: Outer Unit
 ·         Rectus abdominus
·         External obliques
·         Erector spinae
·         Latisimus Dorsi
·         Gluteals
·         Adductors
The core plays an essential role in all of the following:

1.
     Stabilises the spine,  the pelvis and the shoulders
2.     Provides a solid foundation for movement in the extremities
3.     Keeps us standing upright
4.     Enables us to move on two feet, walk and run.
5.     Helps control all movement
6.     Transfers energy into power during sport
7.     Shifts body weight and helps us balance
8.     Generates movement in any direction
9.     Distributes the stresses of weight bearing and prevents injury
10.   Protects the spine from degeneration
11.   Creates a solid base of support for athletic performance
12.   Generates powerful movements in limbs
13.   Transfer energy from the centre of the body out to the limbs
14.   The stronger and more stable the core the more powerfully the extremities can contract
15.   Helps maintain a healthy conditioned body

In my experience the core provides a platform for all aspects of sporting and athletic performance, to neglect the three layers of the core and focus purely on the abs could be affecting your sporting performance and can have long term degenerative affects on the function of the spine especially in competitive sport.

A balanced approach is required to ensure the most effective base for your chosen sport, whether you play for a living or compete for fun.