Its more the fact that UNSW actuaries are boring in general and no one wants to play, maquarie actuaries are a much more tighter group and they bring a lot of imports from other degrees as well. I remember at the indoor soccer comp there was some awesome maq players (seriously doubt they were actuaries) and at basketball we (UNSW) got owned (we barely filled the numbers required).
I doubt much change will happen to the Maq and UNSW events, however you can expect to have more internal UNSW actuarial events this year (after hearing the thoughts of the new social and sports directors).