Again, as badss as Mack was, he couldn't elevate the Raiders, or the Bears.
Do you think he'd have got the Texans past the divisional rounds? I mean Clowney wasn't chopped liver.
Like QB, it takes more than 1 player. The Raiders never had much defensively while he was there. The Bears were already pretty decent, 9th/pts, 10th/yards in '17, going to 1st and 4th in points, 3rd and 8th in yards his 1st 2 seasons there. And he had help in Chicago with several Pro Bowlers and a few All Pros.
Next to JJ in '15, who knows? The Texans were already 3rd defensively that year. In '16 without JJ they were #1. In '18, another big JJ season, every single one of their losses was 7 points or less, except the playoff game, of course. Does Mack help them win a couple of those games, maybe getting them a bye that year? In '19 does he help make it only 35-7 instead of 51-7? That would have least given them a shot at the end.
In the end, I don't really think it makes much difference when you see how the team was slowly being dismantled by OB. No matter who you draft, you still have to have competent leadership. Leadership with a vision, with a plan, with an idea of the value of talent and draft compensation of said talent. That certainly wasn't the case for the Texans as more of the power shifted to OB.