The Detroit Lions lost to the Buffalo Bills 48-42 in Week 15. It was an immediate blitz by Buffalo, with two Josh Allen rushing touchdowns before Detroit could find the end zone. Jared Goff was spectacular in this game but it was not enough, as they fell six points short. The Lions' defense, David Montgomery and Jahmyr Gibbs, and Dan Campbell are most to blame for the loss.
The Bills took the ball and marched right down the Lions' throat in the opening quarter. Their defense has its issues but was able to frazzle Goff and crew on the first two possessions. With two Lions punts and two Allen touchdowns, things were bleak for Detroit. The offense picked it up from there, scoring at will for the final three quarters. But they could not get a stop on defense and things never got terribly close.
This was not a total collapse by the Lions' offense but an expected stumble from a beat-up defense. With a bad running game and questionable coaching decisions, it's no surprise the Lions lost in Week 15.
The Lions need a running game to succeed

Jahmyr Gibbs, David Montgomery, and Jared Goff combined for 48 yards on 15 carries in this game. The duo known as Sonic and Knuckles were both poor running the ball in this game. Gibbs got involved in the passing game, 83 yards and a touchdown, and Montgomery missed the second half with an injury. Those trends must end for the Lions to have success.
There is a lot of conversation around the Lions is about Ben Johnson's wild play-calling. The hook-and-ladders, fleak flickers, and lineman touchdowns all deserve love. But when they are on, they run the ball better than almost anybody. Without that, those trick plays do not work as well. Gibbs and Montgomery must be healthy and productive down the stretch for the Lions to clinch the one seed.
Dan Campbell's risky decision does not work
With 12 minutes left in the fourth quarter, Goff hit Gibbs for a 12-yard touchdown catch to cut the lead to 38-28. The Lions then declared an onside kick and the Bills pounced on it. Mack Hollins returned the attempt to the five-yard line and Buffalo scored easily. Any momentum the Lions hoped to grab from that touchdown was zapped quickly by the missed onside. It was also another example of Dan Campbell's bold decisions backfiring.
Last year, the Lions were burned twice by Campbell's risky choices. They lost a regular season game to the Cowboys because of a missed two-point conversion and they lost the NFC Championship Game because of missed fourth downs. This is the negative to Campbell's coaching style, which has worked overall for the Lions.
The defense of the onside kick is that the Lions had no chance of stopping Josh Allen. Whether the Bills needed to go 95 yards or five yards, they likely would have scored. Campbell may have pulled this off last year when he did not have to declare the onside kick because it was so early in the fourth quarter. Regardless, this decision did not pay off and Campbell deserves some blame.
No defense? No Super Bowl for Detroit
The reason that Campbell went for that onside kick is he has no faith in his defense. They suffered two more injuries and Alim McNeil and Carlton Davis may be out for the entire season. The storybook season in Detroit has taken a significant turn for the worse on that side of the ball. They will need to beat a team of Buffalo's caliber, and maybe even the Bills themselves, to win the Super Bowl, Their defense showed on Sunday they cannot do that.
The Lions hit the road to face the Bears and 49ers in the next two weeks. They will close out the regular season with a home game against the Vikings that could decide the NFC North. The defense will have to show improvements in those games for Campbell to have faith in the group.