This entire Chicago Bears offseason has basically been focused on two players, Justin Fields and Andy Dalton. Fans have been clamoring for Fields to start while the Bears consistently claim Andy Dalton is the guy for now. Whoever plays quarterback is obviously going to play a huge role in how far Chicago goes this season, but this team is still one that can win with defense if things break right.

The offense might not be good enough to make the playoffs unless the defense can step up and be elite once again. Someone is going to have to step up and be a leader of the defense in order to get the group back to being in the top tier.

Here is the Bears' X factor for the 2021 season.

Bears X Factor: Khalil Mack

When the Khalil Mack trade was executed it was supposed to bring about a run of playoff seasons for the Bears. 2018 went well as Chicago had one of the best defenses in the entire league but ultimately a couple field goal posts ended any hopes of a longer run. 2019 came and the Bears went 8-8, missing the playoffs entirely with a lot of quarterback turmoil. Last season the Bears went 8-8 again but, this time it was enough to sneak into the playoffs only for them to lose 21-9 to the Saints.

Khalil Mack has risen and fallen at the same rate as the team. In 2018, Mack had an NFL First-Team All Pro nod. The trade worked as Mack racked up 12.5 sacks throughout the season. Unfortunately in 2019 his production dropped as he only had 8.5 sacks. It's not bad, but it wasn't what the Bears needed from him. He was slightly better in 2020 with 9.0 sacks and now the Bears need him to get back to his 2018 form as the team tries to do the same.

Overall the defense isn't what it was in 2018, but there are still some great pieces. Mack, of course, is the centerpiece but he'll be leading Roquan Smith, Jaylon Johnson and others to what needs to be a great season for the Bears to have a chance. The offense is looking like it'll be league average with either Fields or Dalton playing behind one of the worst offensive lines in the game. The offensive weapons include Allen Robinson, Darnell Mooney, and David Montgomery. It's a trio with high expectations and a lot to prove. Those weapons combined with the quarterback situation and a bad line should equal an average offense.

Taking an average offense and an elite defense makes a playoff team and it was the 2018 recipe for the Bears. It seems like the whole organization is desperate to get back to that level so focusing in on building an elite defense is going to be key. For better or for worse, that all starts with Khalil Mack. If he's back to being as good as he can be then others will follow suit. The secondary will be solid if the opposing quarterback has less time because of Khalil Mack chasing him down.

The Bears traded for Mack because they needed an elite pass rusher to make everything else come together. Fast forward a few years and the Bears are once again in desperate need of a huge season from their defensive leader.