Learn English – a word/couple to express eagerness to win

Actually, I think "win by default" IS often used to refer to this situation. Perhaps metaphorically: We didn't win because there was LITERALLY no competition, but because the competition that existed was so weak that it hardly counted. People will say "practically won by default" or "virtually won by default". But still, nothing in that phrase implies that you (or your team) was weak, just that the competition was very weak relative to you.

Barring that, I don't know of a phrase in that form that explicitly means, winning because the competition was so weak. I can't swear that there isn't one, but nothing comes to mind.

People say "it was an easy win" meaning you were much better than the competition. Again, though, doesn't necessarily indicate that your side was weak.

"The competition was weak".

That's all I can think of.

win win

adjective

advantageous or satisfactory to all parties involved

a win–win situation

a win–win deal

a win-win outcome

I've also heard win-win used as a noun in speech.

"It's a win win for everyone."