Khalil Mack had the best season a Chicago Bears pass rusher has had in 26 years in 2018. He became the first person to break past the 12-sack barrier since Richard Dent in 1993. He finished with 12.5. On the surface that is a tremendous year. Expected of a superstar like Mack. However, the popular saying is the devil’s in the details. When one starts to dig into it, what the 27-year old accomplished is nothing short of astounding.

Start with the circumstances of how Mack came to Chicago. He was holding out the entire offseason and training camp from the Oakland Raiders. His goal was a new contract he felt he’d earned. New head coach Jon Gruden, who was doubling as GM, grew tired of the standoff. Rather than work to find common ground, he gave the green light on a trade. GM Ryan Pace pounced, working out a deal that became official on September 1st, bringing Mack to Chicago.

People were ecstatic and for good reason. A Bears defense that had finished in the top 10 in 2017 suddenly added one of the two or three best defensive players in football to their lineup. The only concern was preparation. Mack hadn’t been through any camp practices. He was completely blind to the Bears’ scheme and the season opener wasn’t far away.

Not that it mattered. He finished his first game in a Bears uniform with a sack, a forced fumble, a recovered fumble, and a pick-six touchdown. An incredible debut. Yet the obstacles didn’t stop there.

Khalil Mack was also held back by injury and his own coaches

There was also the fact that Mack dealt with a nasty ankle injury midway through the season. One which cost him two games by absence. He also tried to play on it in two others. So essentially his 12.5 sacks came in 12 healthy games. Still not impressed. Well, Andy Benoit and Gary Gramling of the MMQB provided the finishing touch.

They provided an illustration for how former Bears defensive coordinator Vic Fangio, for all his success, had a major hand in holding his best player back at times. Benoit explained how the scheme had a lot to do with it.

“Vic Fangio, he’s now in Denver of course but he was in Chicago last year as their defensive coordinator, kind of brings us full circle. We’ve talked about the Chiefs, who drop eight into coverage. We’ve talked about the Ravens, who dropped six into coverage and rushed five. And the Bears—and now the Broncos—they rush the traditional four but will drop a defensive end into coverage because they’re trying to create the effect of a blitz without actually blitzing.

Fangio has done that a lot. Even with Khalil Mack last year, there were a lot of instances where Mack would drop into the flat. Or on base downs, on first and second down if the Bears were in their base package, you can make an offensive formation dictate that Mack would walk out over the slot.”

So how much did Fangio keep a leash on Mack? Gramling delivered the numbers and they are rather shocking.

“I was playing around with the numbers today, how frequently players dropped into coverage, and the league average for edge players dropping into coverage was 8.1 percent. I was surprised to see Mack up there at 12 percent.”

Think about that. Mack had 12.5 sacks with no offseason preparation, losing four games to an injured ankle, and having his pass rush opportunities limited by his own coach. Imagine what might’ve happened had he been able to rush the additional 3.9% near the league average. The devastation might’ve been much, much worse.