If you are doing hundreds of reps of crunch variations on the floor after your workout then you are on the wrong path. Working your abdominals in high rep isolation movements will do as much for your core strength as doing light cable chest flys would do to increase your bench press. For a weightlifter, the most important role the core plays is to provide stability between the upper and lower body during heavy lifting. A weak lower back is going to limit your deadlift no matter how strong your hamstrings are. If your abdominals cannot create stability in a stretched position during a squat, then your lower back and hips will face unnecessary pressure while trying to stabilize your pelvis during the movement.