I kinda agree with both here.
On one hand, Straightblaster is correct in saying that harcore training, a lot of contact sparring, fighting, etc. really will harden you into a combat athelete that CAN take out most untrained people. Simply because a lot of "untrained" people are really not all that tough.
On the other hand, Bri is correct about the dangers of experienced fighters who don't necessarily have 'martial arts" training. Anyone who has seen and been in a fair amount of violence knows that they are not invincible, and that underestimating someone in a street assault is a dangerous move.
A true "pro" on the street will not throw hands with you. A lot of times you won't know who the "pro" is until he lets you know. And by then it's usually too late.
Your training has to go beyond just the physical and has to delve into a lot of the mental and psychological components of these kinds of attacks. That means lots of contact scenario drills, adrenaline dump management, sucker punch drills, hidden weapon attack scenarios, combat firearm tactics, OC tactics,
verbal de-escalation, pre-emptive strike training and justifications, etc.
A true criminal is not going to come up and try and fight ANYONE who remotely resembles a strong fighter. You'll never see him try and throw "haymakers" at a Mark Coleman.......but he will talk to him, ask him for the time or other such things, while three of his associates attack from behind with guns already drawn.
If you want "real counter assault" tactics you've got to look outside most martial arts. That's not to say the physicality of martial arts won't help you (a trained fighter will take out most untrained people..) But most "untrained" people don't fight.
Ryu