Hi. You could make summary fields eg. Total of Hits, Total of AB. NB - not calculation fields using GetSummary function. Then a calc using those summary fields (TotalofHits divided by TotalofAB) to give your batting average. Throw those three fields into your subsummary part and it should work. Remember that when you change your sorting you also need to change the sub-summary part so that it is based on the same sort field.
I am missing something. I created a calculation field, sumCalc_BA, that uses the Summary fields, Tot Hits & Tot of AB, with the calculation, Tot Hits / Tot of AB. I am sorting the layout on sumCalc_AB and set the sub-summary part definition to show the sub-summary, when the sort is sumCalc_BA. I only get the first sub-summary with an incorrect sumCalc_BA. It seems like it should be straight forward, I think I tried this approach before I used a getsummary function, with a similar result, any thoughts.