If you got a punching bag and measured the punches of fighters you would be right a lot of fighters today may puch harder because they weigh more.

Actually landing that punch is a fight against quality opponents is much harder to do.

Punch power makes up a lot of things more than just weight it includes speed, accuracy, timing, technique and experience.

To knock someone down and out at the highest level takes years and does not come over night.

Guys like Louis and Shavers fought the best in their era and demonstrated their power against the best chins of all time.

Do not demean what they have achieved ever.