It wouldn't surprise me if the NFL knew about NE for some time and once Mangini spoke out publicly on it then the league did something, like bury it LOL. It doesn't sound like Goodell viewed the tapes but had them erased. It wouldn't be surprising if it were more than 8 tapes but NE destroyed many beforehand. Sure, other teams may have been recording signals too, but it's the degree to which NE did it I'm concerned.