It doesn't lessen the pain for the Buffalo Bills and their legion of loyal fans that the step they've taken backward this year was predictable after last season's leap forward.

Retooling can throw a wrench into expectations, and that's happening to the Bills after a magical 2017 season under first-year head coach Sean McDermott.

They ended a 17-year postseason drought by making the AFC playoffs as a wild card with a 9-7 won-loss record.

They're 4-9 and out of playoff contention going into Sunday's home game against the Detroit Lions, who've also taken a step back after a 9-7 record that was not good enough to make the NFC playoffs.

A roster overhaul was planned under McDermott and general manager Brandon Beane regardless of last year's record that revived the fan base.

"It was just amazing to see how it brought a lot of energy to our city and fan base," McDermott said of the 2017 season in a conference-call interview with the Detroit media. "That was probably a once-in-a-lifetime basis, in terms of breaking a streak."

The Bills won't have a mini-streak of two straight playoff appearances. A quarterback change was the key roster move and a primary reason for the offense's ineptness.

Veteran Tyrod Taylor was traded to Cleveland in March for a third-round draft pick. The Bills filled that spot for the future by drafting Josh Allen of Wyoming with the seventh pick in the first round.

Allen is talented but raw, and lacks a supporting cast that could make up for his inexperience. The offense ranks 31st in yards and points per game.

For example, wide receiver Zay Jones, a second-round draft pick, leads the Bills with 44 receptions. He is tied for 63rd in the league. Running back LeSean McCoy is next on the team with 29 catches.

The defense does not have a serious weakness at any level. It ranks first in the league in total yards, passing yards and points allowed per game.

It can dominant at times, as was the case in a 27-6 road win over the Vikings in Week 6. The Bills, who were 17-point underdogs, sped to a 17-0 lead in the first quarter and took the Vikings out of any semblance of a balanced attack.

The Vikings ran the ball only six times for 14 yards. Quarterback Kirk Cousins was sacked four times, had one interception and lost two of his three fumbles. The Vikings' only points came on a touchdown catch by Kyle Rudolph with less than three minutes to play.

Allen, who missed four games with an injured elbow sustained in a Week 6 loss to the Texans, has been far more dangerous as a runner than a passer. He leads the team – and all quarterbacks -- in rushing with 490 yards, 7.4 yards per attempt and a team-high five touchdowns.

His inexperience shows in his passing stats – a 52.4-percent completion rate, five touchdowns and nine interceptions. He has a 3-5 won-loss record in eight starts.

Patience is required to stay the course in the plan the Bills have chosen to implement.

Allen is one of 13 rookies on a roster that has 25 active players who have played two NFL seasons or fewer.

"That's one of the challenges of doing what we did," McDermott said in a conference-call interview with the Detroit media. "The goal is not to be in the playoffs. The goal is to obviously win the Super Bowl.

"Making the playoffs is a step and we did that last season, but every season is different. We've got a number of young players who are playing.

"You have to fight through some of these growing pains and learn the lessons that will catapult us, hopefully, forward in the next months and years to come.

"We're paying, in some ways, for the sins of the past if you will. But at the same time, we're excited about where this team is headed and the progress it has made although it has not been on the scoreboard every week."