My feeling is he played flanks, normal or attacking, short passing, possibly high pressing, and may have had up arrows on his MCs as well as his 4 flank players. I wouldn't dwell on it. (5 saves for your GK with a 6 rating? Hmph)

I've noticed my AMC can do great with an up arrow when opponent's DMC has a down arrow. Perhaps the 4 down arrow defenders opened up space for his midfield, since they had best ratings. Maybe the low press+ arrows allowed too many shots from outside the box, which could be easier to save and account for your GK rating. I notice my D line sometimes needs tweaking, like my DR might need an arrow to position himself aggressively.