I don't think you interpret what you see correctly. The only quote to measure XMR performance is XMR/BTC, at least for the time being. XMR/USD is a mere recalculation of the former vs BTC/USD. If anything, this drop in BTC can actually help XMR to climb a bit higher.
Yes, I agree with you. I'm referring to the dive of USD value.
If we look at XMR/BTC, it stayed the same at around 0.016 BTC.
So it didn't dive? Why would you value XMR is fiat? Only metric is relative value to the crypto king XBT.
Exactly, XMR/BTC is what matters. He was referring to XMR/USD when he mentioned the dive. Now XMR/USD = XMR/BTC * BTC/USD, so nothing is happening to monero, it's bitcoin that's weakening. Therefore if BTC/USD changes then XMR/USD must change too, it's a simple math. Of course unless monero in itself (that is, XMR/BTC) changes.
P.S.: if you really wanted to know what is happening to a particular currency you would have to first make a matrix of all mutually influencing currency pairs, calculate how much they contribute to the basket, normalize them so that you don't compare apples to oranges and then you would be able to actually calculate the relative strength of each individual currency, i.e. which currency is driving and which is driven, so to speak.
If you are still unsure what I am talking about consider this situation. Trump says something stupid. People start selling their USD and buying EUR, gold, bitcoins. Thus you will see all those respective exchange rates changing, but that doesn't mean that EUR is going up, gold is going up, bitcoin is going up, it only means that USD is going down and all those others are being driven up. It's the matter of cause and effect.
In fact in this example you would see changes in the other USD-quoted exchange rates as well even if nobody would be buying or selling them. For example, you have EUR/USD, GBP/USD and EUR/GBP. If USD goes down (thus EUR/USD goes up) and EUR vs GBP stays the same then you will see GBP/USD going up simply because GBP/USD = EUR/USD / EUR/GBP, it's just a math. That's what many people don't understand when they see an exchange rate changing without any underlying volume. Just because something is moving doesn't mean both sides are equally responsible.
(sorry for multiple edits)