Delay works like this.
Delayer POV: Hits to where you are going
Your POV: Hits you directly while being close to you, but delayer is gone from that area.
Delayer POV: You swing directly at them while being close to them
Your POV: You swung where delayer was going and the registered a few seconds after.
So basically you both have to swing early to beat each other.
There is no advantage with delay, matches take forever, and is boring.
I would say delayers only have an advantage against people who don't know about their delay before the match, and when their opponent is someone who doesn't know how to fight against delay.
Oops, forgot. Yes, Delayers do have high ping. Generally they can range from 50-500 ms higher than you, depending on what time it is on the server. Anything above that, and it's just pure lag and warp spars.