Brisbane to Mackay / No. of Flights / No. of Flight Cancelld / % Cancelled
QFLink / 108 / 103 / 4.6%
VA / 144 / 1 / 0.7%
So the point of whether they are QFLink or QF mainline or not doesn't matter - your flight is still more likely to be cancelled if it's operated by QF than VA.
If QFlink has 108 flights and 103 are cancelled, thats not a 4.6% cancellation rate