Tag Team Arena: Even if you win, you lose.
According to Tag Team Arena's help section: "The first player to win 2 Battles wins the Series" and "Lose 2 or more Battles, and you'll and up losing". However, the reality can be quite different.
At various times I have come across players putting a very strong team and two other extremely weak teams to defend. That way, even when I win the Series, that defeat makes me lose a lot more points than I won with the victories.
In the end, there is no meaning in winning the Series, because if you are not victorious in the three Battles, you can still lose points.
The same result appears in my defense log. Those who fail to defeat my strongest team end up losing point.