Some of the difference may be that the Leaf file has a modified curve to it, courtesy of LC10, whereas the Phase file is a linear (unmodified) curve. Obviously, sharpness is another issue.
From the site:
No unsharpening. Colour(mode) was set to standard or neutral if possible and grey-balance was picked from the Gretag: s colorchart. If the program allowed I left the curve linear but in some programs that was not possible. (i.e. Leaf Capture 10)
The effort is appreciated, but as has been pointed out, the execution is flawed (like most tests of this sort).
More importantly, this test is very dated. These type of testes are only good for a period of a month or so. Software plays far too important a role in image quality. And these tests are many versions ago. Image quality has changed significantly from Phase One, Leaf, Sinar and Hasselblad several times since these tests.
These tests do more to confuse than clarify - best intentions aside. It may not be easy, but when you're spending $20K - $30K, and hoping to use the product for 5-7 years, you have to test it yourself.
Ok, my wife is kicking me off now - Happy Thanksgiving everyone.