Posted by AchillesHeel
I can only assume that pro boxers would school MMA fighters in striking.
You assume correctly...if they had a chance to box.
But it was proven very early in the sport that was not enough. Think about the gap in boxing talent (and weight) between Art Jimmerson and Royce Gracie or James Warring and Renzo Gracie or between Antonio Inoki and Mohammed Ali or Tom Erikson and Matt Skelton. The difference almost can't be exagerrated and yet the guy who was completely overmatched won because of their jiu jitsu or wrestling prowess.
The very best wrestlers in the world will be focusing 100% on wrestling for the prime of their careers and, as a result, they won't learn the requisite boxing/kickboxing and jiu-jitsu to compete at the highest levels of MMA. The very best boxers in the world will have spent 100% of their focus on boxing and not know how to wrestle or do jiu-jitsu well enough to compete at the highest levels of MMA.
If you're looking for someone who trained exclusively at some other sport--boxing, wrestling, football, rugby, etc. to come in and smash everyone in the MMA circuit, don't hold your breath. People have been (wrongly) expecting that for years. But if you expect a young guy to fight as an amateur boxer at the same time he trains jiu-jitsu and come along in a few years boxing the ears off of the current crop of MMA fighters then I think you're going to be vindicated.