You can't see stats of previous season.

Every player "loosing" a star (or 20%) every season you promote.
Where are my players' stars? - Top Eleven be a Football Manager


The players are K Sandquist and B Eivasi, before the switch they were close to 7* both (117 and 118%), but after the reset, Eivasi dropped to 87% but Sandquist dropped to 97% (normal drop I would assume)
Probably you don't remember well.
I don't remember such a case in the forum - a decrease of players skills in the new season/level.