But the better team is also more likely to score against the lesser team? And you could say that either team will not have exactly equal opportunities to do anything in any given game?
I think I see what you mean. I think your point works if the opportunities to gain an advantage by infringing the rules are equally great for both the defending (inferior) team and the attacking (superior) team - in other words, for every time the defending team fists the ball off the line without the ref seeing, the attacking team can retaliate by diving to win a penalty. This is probably the case in a match considered discretely, but I think there may be problems once a wider context comes into play.
For instance, in the case of a runaway winner to a league meeting a succession of teams fighting hard to stay out of the relegation zone, one would expect unrepresentative (levelled, in this case) results to ensue, as the inferior team stands to gain more by cheating than the superior team does. The superior team would have nothing to gain from extending a 3-0 lead, but the inferior, struggling team would have everything to gain from cheating in order to prevent that lead from becoming any greater. One would thus expect defensive fouls not to be counter-balanced by offensive underhandery.
So, in the context of the standalone match between the championship leader and the struggler, one can say that the struggler has brought about an unfair result. In the context of the struggling team amongst other strugglers, also playing the leader, there may not be
comparatively unrepresentative unfairness, as one can expect the other struggling teams to have levelled results through illegal play
to the same extent.
Consequently, the bottom half of the league table may be 'fair' (the results are representative of actual comparative strength) but the top half 'unfair' (the results are not representative).