I believe you are correct about the order of "most" to "least", like human food.
Agree also that the changes affected lots of kitties, which is what prompted me to call them in the first place. I personally walked away from the phone call satisfied for 2 reasons - A) because my main concern was FF rather than Friskees, because Bob was eating nothing but FF, and heading towards remission at the time, and I sure as heck didn't want to have to find another food when that one was working so well for him. And B), because the magnesium vs. manganese, given the information I got when I looked up the side effects of magnesium, fit well with the symptoms that everyone was describing. So in my mind, mystery solved. All the side effects could be explained by just the one change she mentioned. I didn't pursue it any further, because I personally didn't feel it necessary. And actually there was a C) for me....because my other kitty was eating just Friskees Pates, and fortunately, he didn't experience any ill effects.
I did also encourage anyone who had concerns, or continued to experience problems, to contact them personally, which is the advice she asked me to pass on.
I understand your frustration completely. And in your place, I'd call Purina and ask to speak with Ashley (and call her on it if you think she misled or lied about it). IMO, she answered the questions I asked, and I passed on the info. I don't know if the cats that were having problems still do, or if the owners switched because of the problems. Maybe bring the issue back up again and find out if people are still having the same symptoms? Some of them may have already called Purina and found out some more information.
Carl