Forget posterior chain, glute medius, transverse abdominis and all those other reductionist, mechanistic ways of looking at the body. Instead, step back and look at the whole kinetic chain. Look at how everything is 
connected. Look at how the parts interact and work in synergistic patterns to solve movement problems. To analyze motion look at how everything links, syncs and coordinates. See if there is a flow, a rhythm that allows natural use of gravity and ground reaction forces to produce or reduce force. Look at movement as a big dance with varied rhythms and tempos. Look at how all systems of the body work together continually to produce efficient movement. Just like it is futile to isolate muscles the same is true with trying to isolate systems of the body. Everything is neural everything is metabolic.
Once you understand the connections in the body then the key is to connect the train
ing of the body to the activity being trained for. To make that connection demands an understanding of what the body can and cannot do relative to the demands of the sport. Recognize that everybody is different; everyone has a unique movement fingerprint that allows them to do what is necessary for them to achieve the desired action in the sport. Too many times we try to fit the athlete to the sport instead of adapting the sport to the athlete. Make connections and you can’t go wrong!