Your rotational movements (transverse plane) during games must be powered primarily through your legs to your core. If you have a weak core, that's where your power shortage will happen.
Training in the transverse plane of motion is critical for you to succeed as an athlete. The transverse plane is an imaginary bisector that divides the body into top and bottom halves. Movements in the transverse plane are primarily rotational. Obviously, this will be a dominate plane of motion for many athletes. Baseball players (swinging, turning, pivoting, etc.), football defensive backs (hip rotations, quick turns, etc.) are just two examples.
Traditionally, athletes have been trained primarily in the sagittal plane of motion. The sagittal plane is an imaginary bisector that divides the body into left and right halves. Movements in the sagittal plane include forward-backward and up-down movements relative to the body and/or joint. Examples would be walking, running, bicep curls, leg curls and seated back rows.
Traditional training techniques (such as training with machine weights) have focused on the sagittal plane of motion. This is not an effective training technique if the other planes of motion are ignored during training.
You also need adequate training in the frontal plane of motion. The frontal plane is an imaginary bisector that divides the body into equal front and back halves. Frontal plane movements primarily involve abduction and adduction (side-to-side motions).
Abduction takes a limb away from the midline of the body and adduction takes the limb closer to the midline of the body. Some frontal plane movements would be side shuffles, side lunges and lateral bounces/bounding. Quickness and agility movements made by athletes require adequate frontal plane stability, strength, power, flexibility and balance.
Sport-specific training should focus on training athletic movements and not just muscles! The games are played with quick, powerful athletic movements.
Train for all movements in your sport and you will be more successful.