It's not the CTR that matters as those include partner sites.
Its the keyword status, i.e. at risk, strong, etc that tell you how your word is preforming on G.
Average position doesn't necessarliy mean you're not the cheapest guy out there. If they were bidding 0.05 with a 5% CTR, and you were bidding $0.50 with a 1.8% CTR, you would have a higher position, be paying more, but getting less clicks.
Keyword status is based on your CTR rate only on G's site. Partner and content sites don't matter. There is no way to see your exact ctr on G's site alone. So if you get a 10% CTR rate at AOL, but only a 0.3% on G, your work will be listed 'at risk' even though your overall CTR rate could be quite high.