BUFFALO, N.Y. -- Fair or not, the Buffalo Bills' top-ranked defense will likely be remembered for what it didn't do in Sunday's season-ending loss in overtime to the Kansas City Chiefs.

The pass defense, which had shined all season, came up short in the biggest moment and a chance to host the AFC Championship Game on the line. Instead, the Chiefs will be hosting it for a fourth straight season Sunday against the Cincinnati Bengals (3 p.m. ET, CBS).

Now the Bills face questions about what went wrong and what they need to do to compete against the AFC’s top teams.

“We didn’t do what we needed to do when we had them there for that 13 seconds,” general manager Brandon Beane said. “I truly believe if we played them 10 times, it's probably 5-5. ... If we had just finished that game, the way we know how, we're not sitting here right now. We're preparing for another one.”

What happened?

With 13 seconds left and a 36-33 lead, the Bills allowed 44 yards down the middle of the field in two plays to set up the Chiefs' game-tying 49-yard field goal. From the kickoff strategy to the two defensive plays, Buffalo made questionable decisions on each part of the final drive.

“I wish our execution was different,” coach Sean McDermott said.

After allowing 12 passing touchdowns during the regular season (the fewest since the 2011 Baltimore Ravens allowed 11), the Bills allowed three to Patrick Mahomes, who was 10-of-13 for 188 yards and two touchdowns in the final two minutes and overtime. The Bills never got the ball back after the Chiefs drove 75 yards for the winning score on their first drive in the extra period.

Buffalo tried disguising coverages throughout the game and blitzing Mahomes proved ineffective -- the Bills didn't get either of their two sacks on their seven blitzes.

The Chiefs found holes in the Bills' defense and attacked it. Per NFL NextGen Stats, Mahomes did not attempt a deep pass for the first time in his career, an indicator of how Kansas City could exploit the middle of the field. The Bills allowed 222 yards after the catch, the second-most they have allowed in any game over the past 15 seasons (243 vs. Bengals in 2013), per ESPN Stats & Information.

Despite finishing a game short of the AFC title game, the Bills are not viewing this season as a step back.

"We were playing really good football," Beane said. "The key is to get in the tournament. I wish we had won a game or two more, which we could have had at least one more home game, maybe two, if I was saying regrets. But I think this team was playing really good football down the stretch."

What’s next?

The future remains bright for a defense that has some important work ahead -- some of which is unfinished business from the last offseason.

The Bills got to work last January building the team to compete with the Chiefs, especially after watching the Tampa Bay Buccaneers attack Kansas City’s offense with their pass rush during their Super Bowl LV win.

Buffalo built up front, drafting defensive ends with its first two picks -- Greg Rousseau and Boogie Basham -- but they weren't very productive as pass-rushers against the Chiefs' offensive line Sunday. Going into the offseason, they're being evaluated.

Rousseau continued to improve after hitting the rookie wall at midseason, and Beane expects him “to be a really good pro for us for a long time.”

Basham was inactive for nine games due to roster depth but showed flashes when he got opportunities.

“This will be a big offseason for him to come in and, as I told him, fight for a starting job,” Beane said. “Don't just settle for a backup, rotational-type player.”

Elsewhere on the defensive line, Beane said defensive tackle Star Lotulelei was not the same player after his battle with COVID-19 during the season. The team could save about $4 million, per Overthecap, by cutting him.

The future at defensive tackle will be with former first-round pick Ed Oliver, whom Beane praised and all but confirmed that his fifth-year option would be picked up. Upcoming free agent Harrison Phillips played well in the second half of the season and could return.

Finding ways to put pressure on Mahomes and other quarterbacks remains a priority. But the bigger question might be how can Buffalo attack Kansas City's dominating speed, which has been an issue for so many defenses?

“That team speed is unique with obviously Tyreek Hill and [Mecole Hardman] and [Byron Pringle]. They’ve got a lot of guys that can fly. And it does impact the game,” McDermott said. “I think not just this year, but evolving with how the game continues to evolve, that we have to continue to evolve with it and try and be out in front of it, all the time."

While Beane clearly referenced adding more speed, it's not the only consideration when making personnel decisions.

“They've still got to be a good football player,” Beane said. “You don't want to put a bunch of track guys out here and say we're going to keep up with them, but they don't have instincts. I'm always looking for speed. Size, speed, like those are prototype things that we're looking for at whatever position it is.”

The other priority of the offseason has to be at cornerback. Outside of Tre'Davious White (coming back from an ACL tear), upcoming free agent Levi Wallace and Dane Jackson, there’s not another starting-caliber corner on the roster.

“We'll have to make some moves, but I wouldn't see us being, like, big spenders or anything like that,” Beane said. “But we'll definitely look to fill some spots from the outside as well as retain some of our guys.”

There's work to be done, but the loss to the Chiefs was a reminder of how close this team is and what it has to build around.

“We have our culture here, and so as we look for the draft, free agency, pieces that fit our culture, obviously they've got to be a good enough player, whatever position they play. But we'll continue to look for the same types of players,” Beane said. “The standard doesn't change.”