Here is what I ACTUALLY said:
The typical attacker on the street may have malicious intent, but is most likely not a skilled fighter. They are typically expecting an easy target, not someone that is going to fight back....and certainly not someone who is a martial artist. So if you survive that initial attack and end up in more of "squared off to fight" situation, chances are you will be facing someone less skilled than you and that will be taken by surprise BY YOU, because they will not be expecting you to put up any kind of real fight. So in some respects, once you overcome the fear and nerves and survive what was likely a surprise attack or sucker punch, this should be easier than facing a skilled competitor that knows your style and is expecting you to "bring it." So if you can't make your martial are work in a hard sparring or competition situation, how do you expect to make it work on the street?
Notice the words "most likely" and "chances are"? I still maintain that the average attacker on the street is NOT your "big bloke" and likely does not have much training or real skill at fighting. Now, contrary to your conclusion, that does NOT mean that they will be "small, weak and uncoordinated." And it also does not mean that encountering your "big bloke" is not possible, just not typical! You are the one creating strawman arguments here!