Whelp lets see. Even with five hundred AP and magic pen, her damage is underwhelming. You have to have five hundred AP just to get an extra hundred damage on her W or E. The only thing that scales even remotely decently is her ult. Nami mid is horrid right now due to her ratios. Pretty much every other mid out there will **** on her. I love Nami. But she doesn't have the damage or sustain to go mid successfully right now.
And hopefully never will, as she is a SUPPORT champion.