Almost the same thing happening. First played a league game against opponent 20 % weaker than me - lost 3:0 away. Then met same opponent in the Cup - changed formation and tactics and won 4:0 and 3:1. Then played in the league again with this opponent and I used same tactics and players just like in the Cup games. He always uses same formation. Guess what? Lost second league game also - 0:2 at home. Trolling at its best.