If bitcoin goes up like crazy, alts go down because everyone wants to jump on the btc train.
If bitcoin goes down like crazy, alts go down too because everyone is afraid that the world is gonna end.
Only when btc stays around a certain level for a while, that's when the alts seem to rally.
That being said, I think XMR is a great hedge against BTC, and also one that appreciates in btc value over time!
XMR has outperformed BTC over most time periods during the last 2 years. Looking at a short period is often misleading because prices make their bigger moves in short bursts, with most time spent in trading ranges (and therefore following BTC).
XMR is a slow-burn outperformer, because most traders/buyers don't appreciate the importance of fungibility until they have a lot of experience.