Sounds like a bogus stat. How on earth can they account for a safety that didn't help soon enough, or zone coverages in which the CB doesn't have a man, per se.
Also "history of the league" doesn't apply. The NFL as it exists now is completely different than it was 10 years ago, let alone 80 years ago. Defenses are now penalized for so much as breathing on a QB wrong and WRs are allowed to push and shove all day but if it even looks like a CB MIGHT have touched a receiver early, he gets a penalty. In fact, a receiver can run directly into a defender and expect to draw a PI or illegal contact penalty. You can't bump a receiver more than 5 yards downfield. It used to be you could bump him all the way downfield as long as he hasn't clearly made separation (it's still that way in high school).