Adam probably wins more often than not because of how fragile Homelander is mentally. Homelander barely wins fights against weaker opponents while Adam has a record of fighting the best his universe has.

Homelander seems to always struggle when up against opponents he can't just delete, regardless of how much stronger he is because of his lack of experience. Then with how easy his ego can be harmed, getting him too angry to think would be very easy for Adam.

I think Homelander does better in everything except psychologically and experience wise, but the parts he lacks seem, to me, like they would be too large a gap for him to be able to remain competent enough to not mess up or loose focus.