Khalil Mack is ripping up the NFL right now. The pass rusher is having one of the most productive seasons of his career since being traded in September from the Raiders to the Bears for two first-round picks. He’s already a frontrunner for the Defensive Player of the Year award this season and has the 3-1 Bears off to their best start in five years.

When the Bears need him most, he’s been making clutch plays that have helped seal games. It’s hard to put a number on that, or how much the Raiders are suffering without him.

But using Pro Football Reference’s Expected Points Added (EPA) stat, we can get a glimpse at the game-changing force that Mack has been for the Bears. We can also look at the lack of playmaking on the Raiders defense. To an extent, comparisons can be made between the two defenses.

Here’s how Pro Football Reference defines EPA:

“Expected points represent the estimated point value at the start of a given play, based on down, distance, and field position.”

In a “features” post that further broke down EPA, Pro Football Reference used a 2-yard touchdown by Victor Cruz in Super Bowl XLVI give a deeper explanation of the stat.

Using what teams are expected to accomplish in certain situations we can assign a number to the devastation that Mack brings. Since positive EPA plays are generally good for offense, the EPA numbers for Mack are going to be negative because he’s single-handedly taking points off the board for opposing offenses.

Here are the top five plays that Mack has made this year, according to Pro Football Reference’s EPA numbers.

Play 1: 27-yard pick-six against the Packers

Down & Distance: third-and-19

Location: Packers’ 30-yard line

EPA Difference: -6.11

The Packers were just trying to escape what had turned into a disastrous drive in Week 1. It was third-and-19 on their own 30-yard line — rightfully, Green Bay coach Mike McCarthy just tried to avoid a big defensive play by calling a screen.

Then Khalil Mack happened. Center Corey Linsley let go of the man he was blocking a little bit too quickly and it caused DeShone Kizer to rush the screen pass. The ball ended up in the hands of Mack, who ran it in the rest of the way for six right before halftime to give the Bears a 17-0 lead.

Remember, this play came just a week after he was traded from Oakland to Chicago. Mack was an addition that provided an instant impact for the Bears.

Play 2: Strip sack against DeShone Kizer

Down & Distance: third-and-9

Location: Chicago’s 9-yard line

EPA Difference: -3.70

Kizer had a rough debut as a Packer, as short as it was. Green Bay was in prime scoring position on the Bears’ 9-yard line. The Packers were expecting to get at least a field goal out of this drive just based on where they were set up on the field.

After feeling the pressure from Leonard Floyd, Kizer walked himself right into Mack’s lap. Mack pulled off one of the best plays we’ve seen so far this season, snatching the ball right out of Kizer’s hands for the strip sack.

This play took expected points off the board. Looking at EPA through the lens of Mack clears up the overall usage of the number. These are the type of plays that can win games — unless Aaron Rodgers decides to return to the game and put the team on his back, that is.

Play 3: Strip sack against Sam Bradford

Down and distance: second-and-8

Location: Chicago’s 21-yard line

EPA Difference: -3.63

Again, Mack came up with a play when the Bears defense needed it most in Week 3. Arizona was in field goal range on the Bears’ 21-yard line.

Mack did his part in eliminating the Cardinals’ chance for points: He forced a fumble on a sack that was eventually recovered by his teammate Danny Trevathan.

Arizona went from being in field goal range, to handing the ball over to the Bears. That’s a game-swinging defensive play. The Bears ended up winning 16-14, so the Cardinals not even having the chance to get a field goal here cost them at the end of the game.

Play 4: Sacked Sam Bradford for a 7-yard loss

Down and distance: third-and-8

Location: Chicago’s 32-yard line

EPA Difference: -1.69

Mack was a terror against Arizona. On third-and-8, the Cardinals were on the Bears’ 32-yard line. That’s about a 45-yard field goal — not impossible, but not an easy kick either. If the Cardinals had come away with an incomplete pass, it would’ve been a reasonable field goal attempt.

Instead, Arizona suffered a 7-yard loss on a sack by Mack. That knocked the Cardinals out of their preferred field goal range and they ended up punting the ball to close the second half — in a game that they ended up losing by two points.

Play 5: Strip sack against Russell Wilson, recovered by Seattle

Down and distance: third-and-17

Location: 50-yard line

EPA Difference: -1.21

Seattle was likely doomed here. Third-and-17 at the 50-yard line is essentially no man’s land. It’s even worse when you’re facing a player like Mack, an absolute terror as a pass rusher.

The fumble ended up being inconsequential since the Seahawks landed on it, but the sack helped the Bears offense by getting them into better field position for their next drive — a drive where they got a field goal.

The Raiders could use a defensive playmaker right now

Mack has three plays worth at least a -3.63 EPA difference this season. The only Raiders defensive lineman with more than one is rookie Maurice Hurst, who forced a fumble on a strip sack deep in Cleveland territory against Baker Mayfield.

EPA probably gives us the best chance to whittle down a player’s performance to a singular number. We can assign a tangible point value to player production on a play-by-play basis. While EPA is useful in assigning a number to the outcome of specific plays, it’s not a perfect translation to what Mack would be doing if Oakland had decided to pay him instead of trade him.

However, it is noticeable that the Bears currently sit at first in sack percentage while the Raiders rank dead last. Last year, the Bears were sixth in sack percentage while the Raiders were 24th.

The number of turnovers between the two teams is apparent too. The Bears are second in the league (behind the Browns) in forced turnovers with 11, and the Raiders are tied for 19th with five. The Bears have a more talented defense than the Raiders overall, but Mack has forced three turnovers of his own this year.

When it comes to game-changing plays that put the ball back in the hand of the offense, there might not be anyone better than Mack right now. It’s not hard to think the Raiders could be 2-2 or perhaps even 3-1, rather than 1-3, with the sacks and turnovers that Mack brings.

Outside of the Raiders’ season opener against the Los Angeles Rams, all of their games have been decided by one score — and they led at halftime in all three of their losses. They have an eight-point loss against the Miami Dolphins and a one-point loss to the Denver Broncos. In their games against Miami and Denver, they combined for just one forced turnover and two sacks.

It’s impossible to say that they would’ve outright won those games if they still had Mack, but Mack has already shown he can erase scoring opportunities by himself.

As the great Jon Gruden said about pass rushers, “It’s hard to find a great one.” The Bears have a great one on their hands — an elite cornerstone on their defense for the foreseeable future. The Raiders don’t have that player anymore.