Can someone explain?

[El Duderino]

with 2:0 advantage I would push def, possession and fitness bonuses.

guess you pressed high and hard in the start, leaving your team worn out too soon.

Not at all, played a basic attack, mixed pass. Not pressing, nothing that depleted stamina too much, just a regular offensive set up. The only reason I bonus attacked was because I got equalised out of nowhere. But even then, most of my players were on rather good form.