page rank is a metrics that Google measures and is a kind of authority.
i will explain you what happens when your content is not fresh, lets say your page with High PR but recently, say 6 months you didn't work for fresh content and internet marketing. So your site lacks fresh content, in the mean time, a new web page with fresh content and regular internet activity of content marketing comes up.
Although in 6 months you will not substantially loose PR, but certainly ranking. So winner is who is offering more fresh and updated information. In many cases new web pages are displayed because of this parameter. It is not possible to rank higher for a Low PR above high PR, all activity being equal. :beer_smile: