well scoring a 9 on the physics portion of the test puts you at the 55 - 67th percentile according the the 2007 statistics. It seems like you should reasonably be able to make that score with reasoning skills and a passing knowledge of the subject (like you mentioned). Now what I'm really talking about is mastering the subject allowing you to score that 15...not a 9.
http://www.aamc.org/students/mcat/examineedata/combined07.pdf
To say that the MCAT is not a knowledge test is a bit disingenuous. Is it a purely knowledge based test? No, it involves reasoning as well. Can you do reasonably well on the MCAT with excellent reasoning skills? Yes. Will you be able to score a 15 on the MCAT with only reasoning skills and no knowledge. Absolutely not. You can't say the MCAT does not test knowledge, however you can probably say that it doesn't ONLY test knowledge. Your purported truth is getting a bit hazy.
I'm not here to get in a e-peen size contest though. The point is, the MCAT is designed to account for the different standards in the thousands of universities throughout the US, Canada, etc. Doing well (90th percentile or higher) on it takes many skills, including the knowledge you should have obtained while getting that "B" in Bio 1.