Which is why it would be a major risk to draft an OT that your project to move to OG that high. Given that Campbell was a highly rated prospect coming out of high school, I doubt that he has ever played OG and I don't recall him playing OG at LSU. It seem likely he could make the transition, but that's a lot of risk at #9.
And as has been mentioned, if you think he is an OG, you better be really sure he's a HoF Guard or a perennial All-Pro.