ORCHARD PARK, N.Y. — Wasted opportunity. That was the consensus inside a quiet Buffalo Bills locker room Sunday following their disappointing 17-13 loss to the Kansas City Chiefs, and even a quieter locker room Monday.

The Bills were looking to go 6-3 for the first time since 1999, the last season they made the playoffs. They had the Chiefs at home for a game that was critical in terms of the tiebreaker situation in the AFC playoff chase. Naturally, as the Bills have become well known for, they found a way to blow a game in which they were seemingly in control of from the opening kickoff.

“It’s devastating,” safety Aaron Williams said.

Egregious mistakes in the second half sabotaged their day, highlighted by a pair of fumbles that resulted in a 14-point swing, not to mention some dubious play-calling on their final series when they had a clear chance to pull the game out.

Now, at 5-4, they are in serious trouble in their quest to end their 14-year playoff absence. All four losses have been to AFC teams (New England, San Diego, Kansas City and Houston). They now trail the Patriots by two full games in the AFC East, and the Chiefs and Chargers — who figure to be prime competition for a wild-card berth — have the tiebreaker. Further, the Bills could have gained even more ground with a win because Miami (5-4) and Pittsburgh (6-4) both lost.

“It lingers bad,” said Williams. “That game was ours and we all knew it, and we gave it away. We can’t give away games like that, especially AFC games, especially home games. Good teams find a way to win, and we just didn’t find the big plays that we needed.”

“We definitely lost an opportunity,” said coach Doug Marrone. “We worked hard to get to a point where we had the ability to win this game, being the first game of the third quarter. We’ve lost an opportunity. We had an opportunity to get to 6-3. Now we’re going to have to fight our way back and come back and find a way to win our next game.”

That next game is against the Dolphins, in Miami, on Thursday. The Bills routed Miami at home in Week 2, but the Dolphins — despite their loss Sunday in Detroit — have been playing much better. And, it’s no secret that home teams generally have a sizable advantage in the Thursday night games, so this is a tall task for the Bills. A loss to the Dolphins, barring a miraculous finish over the final six weeks, would pretty much end any chances the Bills have of making the playoffs.

NOTES: CB Leodis McKelvin had a brutal day. In addition to his game-changing fumbled punt, he was targeted 11 times in coverage and gave up seven catches for 77 yards. … DT Marcell Dareus had another huge day with three sacks, giving him a career-high nine for the season. … DE Mario Williams recorded a sack for the sixth game in a row, a streak that ties his career high and not accomplished by a Bill since Aaron Schobel in 2006. … DE Jarius Wynn left the game with a knee injury in the fourth quarter. … WR Marquise Goodwin suffered a rib injury in the fourth quarter and could not finish the game.

REPORT CARD VS. CHIEFS

–PASSING OFFENSE: C-minus — This was not one of Kyle Orton’s finest moments. He completed 29 of 48 passes for 259 yards and a touchdown and did not turn the ball over, but he did not shine down the stretch. He threw four straight incompletions from the Chiefs 15 in the final three minutes that ended the Bills’ chances of winning. The offensive line actually had a decent day against a very strong KC pass rush and Orton was sacked only once. WR Sammy Watkins played, but wasn’t 100 percent and it showed. Chris Hogan caught five passes, including a 25-yard TD in the first quarter.

–RUSHING OFFENSE: C — The Bills finished with 111 yards, including 62 by Anthony Dixon, meaning it was their best day since the Week 2 victory over Miami. However, they got away from the run game in the fourth quarter, passing 17 times as opposed to two run calls, even though they started the quarter ahead by 10. On the last possession, when they reached the 15, there was no reason why they shouldn’t have tried a run or two. Bryce Brown had 35 yards, but lost a fumble near the goal line in the third quarter.

–PASS DEFENSE: B-plus — The Bills generated great pressure with six sacks of Alex Smith and pressured him on numerous other plays. They held the Chiefs to 177 passing yards, and only two plays went for more than 20 yards. CB Leodis McKelvin did not have a good day, primarily against Dwayne Bowe. McKelvin allowed seven receptions for 77 yards on 11 targets. Overall, Bowe had eight catches for 93 yards.

–RUSH DEFENSE: C — For much of the game, the Chiefs couldn’t get anywhere, but when it mattered most, they gutted the Bills. Jamaal Charles scoring on a 39-yard run on fourth-and-1 in the fourth quarter was a killer that got the Chiefs back into the game, and his 18-yard run set up KC’s go-ahead TD in the fourth. The Chiefs finished with a 5.3 average per carry and Charles gained 68 of his 98 yards in the fourth quarter. LBs Nigel Bradham and Preston Brown both had solid days, combining for 15 tackles.

–SPECIAL TEAMS: C — One play ruined an otherwise pretty good day for the kicking teams. Leodis McKelvin’s fumbled punt in the fourth quarter was the play of the game and turned it in Kansas City’s favor. Dan Carpenter made his two field goals, punter Colton Schmidt had a tremendous 45.7 net average on a cold, rainy day, and Jordan Gay had three touchbacks on four kickoffs. Marquise Goodwin averaged 21 yards on four kick returns, and McKelvin had a big 23-yard punt return late, but his fumble dragged everything down. It was a huge play.

–COACHING: C — The defensive plan was sound as the Bills put the heat on Alex Smith and were sound against the run — until the fourth quarter when Jamaal Charles got hot. And DC Jim Schwartz couldn’t find a way to get Leodis McKelvin out of a bad matchup against Dwayne Bowe. On offense, OC Nathaniel Hackett dialed up four straight pass plays from the 15, all of which were incomplete, three of which were low-percentage throws. Doug Marrone made some curious decisions in the fourth. He punted on fourth-and-6 from his own 41, and fourth-and-1 from his own 41, then eschewed a field goal late to get within one point (with 2:27 to go and all three timeouts) at the 15 and went for the TD on fourth-and-10. It failed.