So many possible reasons. Did you check out his squad before the match and adjust tactics? Did you look at player strength?

Also, you are not playing against two-star players. His players have four to six stars and their form is good, while your midfield form is bad.

Is that a trend in form? I once had a midfielder who could never get past 6 form and I eventually sold him because of his high value and quality level. If guys underperform often, you may reconsider their starting spots in the team, or sell them altogether.