I think the OPs point here (if I may paraphrase) is that, while AA clearly has the right to do just as they are doing (as other posters have suggested), doesn't the fact that the plane appears to be half empty four days before departute indicate that they are not doing a good job of price management in this case? Models may show the likelihood of the higher-priced purchase, in general, but it doesn't seem to bear out in this case. Shouldn't their model make changes in a case like this to reduce things like YUP fares as it gets closer to departure and seats are still empty?

Cheers.