The second sentence is exactly how a native would phrase it, especially for a very polite apology. The first sentence has bad implications. Unequal terms implies something outside the game has rigged the game. There are a milllion different ways of saying "Their team was really good, but my team was shit". Sports commentators say that same phrase a different way every week. But for you, I would make use of the phrase "part of it". It's a good way to make it clear that an issue has multiple parts. In this case you would say "Part of it was that your team was good, but the other part of it was that my team plYed like shit". As a Liverpool fan after last year, I was saying that last sentence a lot.... our goalie man..

#2 is flawless. #1 is a perfect sentence, but the context is slightly off: Imagine two soccer teams. Team A is stronger than Team B. Saying team A is "stronger" just compares team A's teamwork and skill to that of team B. The only way "we don't fight on equal terms" would be an appropriate response is if you were a member of Team B and you were trying to imply that you (Team B) played fairly according to the rules, and Team A won BECAUSE they cheated.