they later explained it that xavier paid lobo to take a dive.
then again with the MvsDC matches. it's well known that dc only had 1 demand, superman and batman weren't allowed to lose.
at best they had batman admit to captain america that cap would eventualy beat him, but it would be a long and fruitless fight that the both of them would gain nothing from.
so instead they teamed up to find the real enemy.
as for superman, he fought professor hulk and won of course, but they made a seperate version where hulk wins also as bonus pages.