Found myself in a similar position. I managed to draw my league match against a team 7 quality less in the very last minute. All my players went in with above 90 cnd. I used 3-1-3-1-2 formation with normal tackling and hard attacking. The match drew 2-2. I was really angry as I didn't know why??? Is it possible that he used win bonus and so his performance improved? But can it increase by that much?