Of course you have a point, Tyson had no business being in the ring with someone in his prime.
I just thought it looked odd the way he did it, like he started his counter and then pulled it. Normally as you say they would see the opening but not be able to capitalize at all, definately not perfectly slip the punch, line up and then shove instead of punching. The hard part is really seeing the incoming punch, slipping it and moving to set up the counter. In my experience this is the first thing to go, the timing in slipping the punch.