Downtrend is only due to BTC being down. Most don't realize that.
BTC is rated against the dollar or euro.  But ALTs are rated against BTC.
It's a compound effect. So when BTC falls 20%, ALTs should remain locked  or fixed at the price they are at compared to BTC, but they fall too.
So when btc is down is when you should buy the ALTs... Because your leverage is so much stronger when BTc rebounds which it will.
I don't think most people get that.