I've updated the post to reflect the research, but for those who were asking here, I looked at CCM and Perth:
Central Coast Mariners: 3 goals from 167 corners (1.8%)
Perth Glory: 8 goals from 209 corners (3.8%)
Compare that to the Phoenix – 2 goals from 196 corners (1%).
Adding in the study Enzo looked at and acknowleding the sample size I think it's fair to say that the Nix are signficantly underperforming from corners.