Sunday against the Buffalo BillsTHE Kansas City Chiefs lost a football match for the first time since last year’s Christmas Day debacle. Some of the weaknesses of Kansas City’s 9-0 start were even more evident in Sunday’s loss. The Chiefs will need to learn some key lessons and work on three areas of improvement throughout the season to complete the NFL’s first three-peat.

Against Buffalo, Xavier Worthy caught four passes for 61 receiving yards and a touchdown. All of these captures took place in one trip. Worthy scored no goals in the second half of the match. His greatest piece could have been on a long pass where he couldn’t get his feet on the sideline. While Patrick Mahomes could have thrown a better ball and driven it higher up the field, Worthy has to be able to get down flat in this situation.

The connection between Mahomes and Worthy struggled throughout the first half of the season. They haven’t always been on the same page with the deep ball. Strengthening their chemistry will go a long way toward Worthy becoming a more important part of the offense, but the offensive staff needs to find a more consistent way to get him involved. After throwing a touchdown where he was the focal point, he disappeared for the rest of the game. Using his speed on a variety of crossover routes on all three levels of the field can improve the offense and get more touches for Worthy.

Through 11 weeks, the Chiefs are tied for fourth-fewest sacks in the NFL. Against Buffalo, their lack of a four-man pass rush was on full displayand the quarterback could sit in the pocket without worry. While the Chiefs have Chris Jones in the middle of the defensive line, teams have been able to focus on him without another defensive lineman proving they can consistently win one-on-ones. George Karlaftis generated the second most pressure on the team, but he has been less productive in recent weeks against better offensive lines.

Kansas City has invested heavily in Mike Danna and Felix Anudike-Uzomah over the past two years, and they have combined for just 12 total pressures this season, according to Professional football reference.

Get Joshua Uche more comfortable in the system and the addition of Charles Omenihu should give more juice to the defensive line up front. Uche has proven to be a quick and flexible runner during his career and should be able to really help in obvious passing situations. Omenihu is coming off a torn ACL, so he may not return to form right away, but the Chiefs will likely need him to get there eventually.

Despite what has unfortunately been an injury-plagued season for the Chiefs, Injury to No. 2 cornerback Jaylen Watson could have been the most important for the team. Without Watson, the Chiefs defense really struggled. In the weeks Watson played, the Chiefs defense held opponents to -0.066 EPA/game, which was eighth best in the league. Since Watson was removed from the lineup, the defense has allowed 0.078 EPA/play, which ranks 22nd in the league. That’s a dramatic decline, and it was a huge factor in the Chiefs’ first loss of the season.

During Sunday’s game, the Bills continually went after Watson’s replacement, Nazeeh Johnson. The Chiefs were already getting away with poor coverage at the linebacker position by calling on their safeties in the middle of the field more often due to their reliance on Watson and Trent McDuffie on the outside. Defensive coordinator Steve Spagnuolo and his staff have yet to find the answer with Watson out of the lineup, but they’ll need to find it before another team exploits him.

Learn more: Andy Reid on the chances of Isiah Pacheco and Charles Omenihu playing against the Panthers