The pass-rusher has stripped the ball once in each contest this year. He also returned an interception for a touchdown in Week 1.
While Mack has been an elite player throughout his career—earning three Pro Bowl selections over the past three years and totaling 36.5 sacks—his play has been even better since his offseason trade to the Bears.
On the other hand, the Raiders are off to a 1-3 start and have just five sacks as a team, which is tied for the NFL's fewest.
It's clear Gruden misses Mack's production, although he felt his hand was forced after the 27-year-old held out throughout the preseason.
"Obviously, Khalil Mack didn't want to play here," the coach said in September, per NFL on ESPN.
Based on what we have seen in 2018, the Raiders probably should have done a better job of convincing him to stay.