Hi guys,
I just looked at the link. Note that there are a number of meanings listed. #2 is Hoa Thai's, where "sequence" might be a synonym; #1 is Belly's, where "progress" is a synonym.
I think it's safe to say, "We watched the progress / progression of the disease," where "progression" could mean "in stages" or "in a sequence," but it could just as well refer to a gradual deterioration - "quality" in a negative sense.
Edit. My American Heritage also gives the #1 definition as "progress." Ironically, MW Unabridged gives "progression" 2c: the process of advancing especially to a better or higher condition: gradual development
Belly, I didn't elaborate on the first example because I couldn't get a handle on it, although I was sure that "progress" was the correct choice. Having now read Hoa Thai's offerings and looked at some references and re-read the test example, I believe Hoa Thai's analysis applies perfectly to this situation. "Every trend pointed toward" is already pregnant with "progression" in the time sense. What it pointed toward was an improved level of quality.