Dude, it's not destroying evidence, it's called cleaning the carpet.
Look, if your teenage son spills grape juice on the rug after you told him not to run with his juice in the living room, what do you do? I'd think you'd punish him, or yell at him, and then you'd clean the carpet. You wouldn't fence it off with kiddie gates, or put glass over it, to keep it around as "evidence" of what he'd done, to rub his nose in it from time to time, and to show friends and guests when they come over for a drink--"Look what our son did, we can't trust him anymore...".
The actions of the NFL are suggesting "We know what happened, it was bad but it's been taken care of, let's move on and avoid any more mistakes in the future."
Good analogy........ Similarly, you could also use a grown up example most of us can understand too (in case the slow still don't get it).
Let's say that while self-preparing your taxes, you come across a deduction that perhaps you think (however marginally), that you could take and it allows you to deduct and extra grand, saving you a $300 bucks of your tax bill.
let say a year or two down the line, you get audited and the big bad IRS guy comes in a when he gets to that particular deduction, he focus's on it and the conversation go like this, paraphrased in normal-speak. (parenthesis are direct coronations)
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IRS - Dude, what's this sh!t right here, why did you deduct $1000 dollars in strip club receipts under housing allowance. (NFL getting the tape from the Jets)
YOU - Oh, well those were nights the old lady booted me out of the house and I had to go someplace else for shelter and sustenance. Why, is that a problem? (BB's BS excuse)
IRS - Are you nuts? Of course you can't deduct that stuff, and you ought to know better (Goodell's finding them at fault).
YOU - Oh sorry, I thought I could, but I guess not, huh
(lack of a public response from Kraft)
IRS - Well, you can't. We're gonna fine you $5000 and charge you a whole crapload more in interest because of it. (Goodell's punishment handed down).
YOU - {gulp.....}
IRS - Oh yeah, we're tacking on the initial $300 bucks of the money you never sent us and should have never been able to keep in the first place (Give us the other tapes you have)
YOU: Okay, I'm not going to prison though, right.............. (here's the tapes, and the cash)
IRS: Naw, pay your fine and the $300 you shouldn't have and we're square. Though, I'd expect a few more audits down the road and if we find any more BS, we're not gonna be as nice as we are right now. (We're watching you so don't do it again).
CASE CLOSED
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I'd add in this case the tapes themselves weren't that important, only the BB didn't get to keep them. They knew exactly what BB was trying to do and that he thought he could, as long as it wasn't for in game use. The above example is not at the level of TAX FRAUD (or direct cheating) and neither was BB's actions, but it's not something that they will allow you to get away with. Had they thought this was DIRECT CHEATING, they would have banished BB from the league (just as Tax Cheaters go to jail). This isn't that...... and never was.
I'm quite sure that BB/Kraft insisted that, given the leak of the initial tape, they insisted on the destruction of the tapes. In that they did not really matter to the NFL (only that BB not be allowed to keep them). They had no problem with it. If they thought the tapes were EVIDENCE, they'd never have gotten rid of them.
Take off the tin-foil hats and see the case for what it really is.