“Empty handed, professional boxers are the most dangerous men on earth.”
If they get the first shot in, probably. But in a square-off, no rules fight, wrestlers and BJJ guys can cripple you in 30 seconds. Or kill you, if they wish. Depemds literally on the first seconds. They go in low, and if they get a leg a boxer is toast.
The “dirty” moves that grapplers have, outlawed in any ring, can destroy you fast. Break your back, knee, arms, and the all important eye gouge.
Gracie BJJ is brutal, and they fight dirty in training. Dislocations and concussions (from getting the back of your head banged hard into the ground) are common.
But a pro boxer gets in the first punch and it’s game over.
Also, a real good kicker can take out a boxer. Boxers are just not trained to block it. I’ve seen it in UFC. Very few boxers get anywhere there.
The original UFCs had no weight classes at all. Everyone fought everyone. With BJJ man Royce Gracie destroying everyone, and he was 160-lbs I believe, although taller than most. Later good grapplers gave them a run. Dan Severin, HUGE wrestler, 6’4”, 260, almost killed Royce around UFC-6. Royce never came back. Nobody could touch Dan, so they went to weight classes shortly after.