what is google page rank?
Google Page rank is an relative analysis of considering all the websites within a particular industry [eg fashion, logistics, pharma].
Your website's page rank is nothing but your strategic industry position among all the websites of your industry.
so it could be possible that if some website's performance become weaker so it may get less page rank, so automatically it becomes your potential and u get higher page rank.
so competitor's weakness automatically becomes your strength, and your weakness automatically becomes competitor's strength.
so pagerank is not only and only absolute or individual analysis it is relative statistical analysis.
it runs with a algorithm of comparison of all the websites of a particular industry.