With new features of BPM UI Toolkit and CSHS it is now possible to not have to many logic in the CSHS e.g. you define actions for your Coach and handle them in client side Javascript by creating service flows etc.
One way is to use the event handlers of the BPM UI Toolkit e.g. onLoad, onChange etc. Also if you have to switch between multiple coaches instead you can use the "Stack" control to present multiple views on the same Coach similar to tabs but difference being the tab header is not visible in "Stack". The stack control binds to an integer index and the value of the index determines which Stack is visible currently.