As long as one of those "variables" is named Garrett, the rest don't matter. You can load up and kill it in the draft (like in 2016), and Garrett and his staff will still find a way to screw it up if they reach the playoffs (as they did). And you can load up in free agency and have overwhelming talent at every position, and this staff would still only be able to beat the mediocre teams and lose to the good ones (as they've had 7 years to establish). But keep in mind that if just one of those players misses time, all bets are off and this whole house of cards collapses. After all, how can anyone be expected to deal with injuries in the NFL?
Maybe the "Lynch mob" actually knows better than the spreadsheet intellectuals trying to overthink everything? After all, the Ivy League educated coach manages to be a football moron.