Then your point boils down to 'he wasn't able to right the team in 2015.' Fine. Happy to concede that as it's obviously true.
It's also irrelevant, since we all understand what the actual issues were with the 2015 team. Beyond that, if you don't count the job he did righting the ship in 2010 (which you 100% should count as an example of what you were asking for since it being a partial season is completely irrelevant to his ability to do what you were asking about, and he even did it with Romo on the bench, which makes it more impressive), then you're looking at a guy who's had seasons of 12-4, 13-3, and three seasons of 8-8. There's been nothing in need of 'righting' the rest of the time he's been a HC. Because he generally does a good job.