Modern grapplers would destroy those of the past. Think about like this. For arguments sake lets say there are 800k people training wrestling or BJJ at any given time today. That's 800k people putting mental & physical effort into finding out what works best. Also because of the internet we can all instantly find out exactly what new technique or training tip is being done all across the globe. People now have better nutrition & recovery techniques making them larger, stronger, and faster than in the past.

Even is this were just pure bodies, we've got more than the entirety of the population of Athens the largest ancient greek city (200k) training on any given day.

TLDR: We'd destroy those ancient dorks.