I think the outrage about Liza outscoring and tying Anna on PCS (as compared to what will probably happen with Alina and Alyona) is mainly because of this:
Out of the experienced seniors up against the 3A, there's no denying that Liza is the one experienced senior who is practically notorious for having empty programs, little artistry, and just poor program components in general. Few would say Evgenia or Alina have poor artistry, except for the clearly biased. On the other hand, Liza is practically known for having excellent tech but not valuing the artistic side. Come on. She blatantly admitted she audioswapped her program to completely different music. It doesn't get any more obvious than that.
If PCS was based solely on reputation, with Liza's reputation as a former world champion and one of the only ladies with a 3A, she should have had ridiculously high PCS long ago. She could have outdone Evgenia on PCS last year when Evgenia was struggling. But she didn't. Because as much as PCS is based on reputation, to an extent the judges still have to look at what is being delivered on the ice. Liza delivers excellent, textbook jumps, and she has the reputation to back herself up, but artistically she delivers very little, and the judges mark accordingly. As compared to Evgenia and Alina, no one could make an argument for Liza having brilliant artistry or mastery of any of the 5 PCS components.
Whereas Anna, out of the 3A, might not have the best skating skills but she's certainly there on performance, interpretation, and transitions. Her musicality is effortless and her programs play to her strengths. With Alina versus Alyona, as someone proved above, the artistic skill differences are debatable. If they placed Alina a bit above Alyona on PCS, that would be maybe a little unfair to some people, but still within reason. Placing Liza above Anna? Now that is on another level.
Point being: This isn't just a simple black-and-white thing of "You're a new senior so you wait your turn, that's how it's always done", because Liza's constantly low-for-her-reputation PCS proves that PCS isn't purely reputation-based. For a more extreme example (NOT Liza and Anna, this is imaginary), if a reputable senior just skated circles around the rink, demonstrating two-footed skating the entire time, had absolutely 0 transitions, and demonstrated zero performance skill the whole time, and then a new senior came on with brilliant skating skills, complex transitions, and gave an incredible performance - would the older senior outscoring the new senior not come as a shock? Because it isn't as simple as "The new one will NEVER score as much as the older one". Not if the older one is delivering much less than the new one.
The comparison of Alyona/Alina and Liza/Anna is...not really a fair comparison, imo. Alyona and Alina are on a similar artistic level (someone who posted above me showed that it could go either way). Liza and Anna...well, one connects to her music and one took her music out and changed the genre completely without editing the choreo at all. I don't want to diss Liza because she is incredible, no doubt, but to say that she's similar enough artistically to Anna to tie with her on PCS is...not entirely fair.
