Yeah, congrats on the win! I personally wouldn't read too much into the ranking--it's not very accurate, especially for new managers who are always training and getting better.
For example, in my cup game last season
(68620441), I was roughly a month into my BB career and won as rank 1550 against rank 555. They had a 82k player, more than the total salary of my entire roster! For that reason, I'm sure there are better upsets, by your definition, because there are many better ways to compare teams than simply looking at salary and ranking.