We're talking about regular dudes with no fight training
Boxers are trained to take punches bro. Most of them usually spar with bigger fighters who not only puncher harder but know how to get proper leverage on shots
You can have a huge weight advantage all you want, or have muscles but you can't train a chin muscle
Most guys with no fight training going against an elite boxer like Tank are getting stretched bro.
This is what happens when a bigger guy 6'1 180lbs (he was even an too amateur boxer I believe) gets in the right with a "retired" but elite fighter. I time stamped it for you