What separates star defenders Aaron Donald of Rams and Khalil Mack of Bears? Production

Aaron Donald and Khalil Mack were on top of the NFL defensive world as 27-year-olds in 2018.

Donald, the Los Angeles Rams' star defensive tackle, won his second consecutive NFL Defensive Player of the Year trophy thanks to a whopping 20.5 sacks, setting the NFL record for sacks by a defensive tackle. His efforts helped lead the Rams to Super Bowl LIII, where they lost to the New England Patriots.

But as amazing as Donald was, Mack was right alongside him in the defensive hierarchy. The edge rusher, traded to the Chicago Bears from the Oakland Raiders right before that season, was a first-team All-Pro selection, racking up 12.5 sacks and helping lead the Bears to their first playoff berth in eight seasons.

But as the two meet Monday night at SoFi Stadium in Inglewood, California, they don't sit 1-2 atop the NFL defensive hierarchy. Donald, after 12.5 sacks and a fifth straight All-Pro selection last year, has already racked up 7.5 sacks this season and looks to be the favorite for a third DPOY in four seasons (he also won in 2017). Mack, while still a Pro Bowler, wasn't an All-Pro last year and his status as Donald's main DPOY competition has been threatened.

Separated by three months in age, is there a bigger separation happening in production? We ask Bears reporter Jeff Dickerson and Rams reporter Lindsey Thiry to break down the defensive stars.

In 2018, both had monster seasons. Since then their paths have diverged somewhat. What has gone right for Donald and wrong for Mack?

Dickerson: There's nothing "wrong" with Mack. Rather, Mack is a victim of his own success. Most players would be thrilled to finish a season with 47 tackles, 8.5 sacks and five forced fumbles -- Mack's numbers in 2019 -- but Mack raised the bar astronomically high the year before. He failed to dominate last season the way he did in 2018; Mack's first year in Chicago after the Raiders traded him prior to Week 1. The good news for the Bears -- and bad news for the rest of the NFL -- is that Mack is back. He already has 4.5 sacks for one of the league's best defenses. Mack terrorized Tom Brady in Week 5 and even hip-tossed Tampa's starting right tackle for good measure. Good luck, Jared Goff.

Thiry: Ask any teammate, coach or even opponent, and they will tell you that Donald's effort on every play, whether it's practice or a game, is second to none. He does not take a play off, and he doesn't take a day off (even after the Super Bowl appearance, Donald rested only a few days before he returned to his grueling workouts). "He never gets complacent," Rams coach Sean McVay says. "When you watch the way that he works and gives himself a chance to improve because of the consistency and the attention to detail, the focus and concentration that he takes on every single thing that he does, it's good to be around." Donald continues to find new ways to get his job done because of unmatched dedication and hard work.

In what kind of defensive scheme does each thrive most? Offer an example of their best game since 2018?

Dickerson: Mack is a pure, 3-4 outside linebacker. He is so talented that he sometimes lines up with his hand on the ground, but he's most dangerous out of the two-point stance. Mack showed the entire NFL -- in case it didn't already know -- how multidimensional he is when he made his Bears debut vs. the Packers in Week 1 of the 2018 season. Mack became the first player since 1982 to record a sack, forced fumble, fumble recovery, interception and a touchdown in one half.

Thiry: Donald spent three seasons playing in a 4-3 defense, then switched to a 3-4 in 2017 when former Rams defensive coordinator Wade Phillips arrived. New defensive coordinator Brandon Staley kept the base 3-4 in place after he was hired this season. Donald has thrived regardless of scheme, but this season there's an uptick in how often Donald lines up in different spots along the line. "In certain situations, we definitely want to make sure that he's not a static target and in the same spot," McVay says. "It makes it a lot easier to kind of game plan a player of his magnitude when you know where he's going to be." So the Rams and Donald have tried to keep opponents guessing. In a Week 5 win over the Washington Football Team, Donald erupted for a season-high four sacks. "I was single-blocked," Donald said.

How does a team game plan for Donald? For Mack?

Dickerson: Carefully. Block Mack with one guy at your own risk. And if you double-team Mack, that frees up space for defensive tackle Akiem Hicks and pass-rusher Robert Quinn, who roughly played 30-35 snaps per game. Basically, the Bears are really, really tough on defense when Mack is at his best. You better chip the heck out of Mack and get rid of the ball quick. Otherwise, it could get ugly for the opposing quarterback.

Thiry: The 49ers provided a blueprint last Sunday, when they defeated the Rams 24-16. Donald did not have a sack and had only one quarterback hit on Jimmy Garoppolo. "It was a lot of perimeter-type stuff, where you're seeing a lot of those kind of flip play. ... A lot of the toss actions," McVay said. "A lot of the concepts and different things that they were activating to minimize the impact you can have as an interior player, where they really stretched your edges in your second and third levels." Watch for other teams to try to emulate what the Niners accomplished; however, it's likely Donald spent the week figuring out how to beat that scheme.

What has been the Achilles' heel of their respective games?

Dickerson: The supporting cast. The Bears had a ton of injuries last year, which contributed to Mack's decline. Without Hicks (elbow injury much of 2019) or a consistent pass-rusher on the other side (2016 first-round pick Leonard Floyd) teams focused almost all of their attention toward stopping Mack. Through six weeks, the only serious loss the Bears have suffered on defense has been nose tackle Eddie Goldman, who opted out over the summer due to COVID-19 related concerns. Mack is especially dangerous when the rest of the defense is healthy.

Thiry: As an individual, Donald does not have an Achilles' heel. He is dominant in every fashion. The only issue, like Mack, is that opponents are able to key in on Donald because of a lack of dominant pass-rushers coming from the edge this season. Floyd, whom the Bears released during the offseason, has maintained a persistent presence and has two sacks. However, the position opposite of Floyd has remained in flux as the Rams shuffle several players in attempt to establish a more consistent pass rush.

How will each impact Monday night's game most?

Dickerson: Mack is such a force that Los Angeles will have to key on him. Unfortunately for the Rams, Hicks is also having a monster year and is borderline unblockable at times. Safety Eddie Jackson is an opportunistic playmaker. Cornerback Kyle Fuller is a former Pro Bowler. Veteran safety Tashaun Gipson already has two interceptions. Roquan Smith is Chicago's leading tackler. The defense feeds off the attention that is paid to Mack, who impacts games not only by his play but also by his presence.

Thiry: The Bears will have to account for Donald on every snap. Even while facing a double-team on 70.1% of his pass rushes this season, Donald has a league-high 7.5 sacks. And worst news yet for the Bears is that Donald is coming off a down performance against the 49ers that will inspire him to get to quarterback Nick Foles. Donald has not gone two consecutive games without a sack since Week 5 and 6 of 2019. Watch for his pressure to force Foles into some errant throws that the Rams' secondary, led by cornerback Jalen Ramsey, will be ready to capitalize on.

The Bears will win if Mack ... / The Rams will win if Donald ...

Dickerson: ... plays the way he is capable of playing. The Bears need Mack to sack Goff about one or two times and hit him five to six times. The Bears will need to rely on their defense to win. Maybe Mack can also pitch in on offense. That would be helpful, too.

Thiry: ... makes Foles uncomfortable. The Rams' defense has gotten sacks in bunches -- see their eight sacks versus Washington. So if Donald is able to lead the way against an offensive line that has a pass block win rate of 57.3% (16th in the NFL) it could be a long night for Foles and other playmakers on an offense that, at least statistically, is ranked among the least productive in the league.