Player stamina decreasing substantially during matches

This has happened multiple times for me, my players loose their stamina during game very quick, I know at first you will say may be it is because I have put the team on pressing but I actually have not, this does not happen each game only sometimes.

It also effects my new subs in during a match, like a player who has been subbed in at 70th min, will have no stamina left at 85!