Arrows slight up or down, means re-balancing attributes according to his CA. So, if you have a player which have 100 CA - 100 PA will re-balance his attributes for the role which you are using (let's say you are train him as Mez Su, but have attributes for CM At). In that case will lower something else to gain more in key attributes for Mez Su.
It's something normal to be happen, no worries.