The Green Bay Packers are proof of that, with Aaron Rodgers' broken collarbone sabotaging a promising season.
The Atlanta Falcons, who visit the Packers on Sunday, have seen their fortunes change in a relative blink of the eye, as well.
In last year's NFC Championship Game, the Falcons led the 49ers 17-0 barely 15 minutes into the game. The 49ers rallied to take the lead in the fourth quarter but quarterback Matt Ryan marched the Falcons to the Niners' 10-yard line in the closing moments, only for the drive to stall and their season to end.
So, when the schedule came out, this looked like must-see TV and a potential showdown for home-field advantage in the NFC. Instead, Green Bay (5-6-1) and Atlanta (3-9) have been banished from the marquee Sunday night slot and relegated to a noon game.
"I think it's an example of how close the NFL is in terms of competition," Falcons coach Mike Smith said during a conference call on Wednesday. "Each and every year, there's teams that surprise people. I don't think this league this year is any different. It's so close. Most games are decided by eight points or less – over half the games – and between 20 and 25 percent are three points or less. It's a fine line."
Being on the wrong side of that fine line in close games sent the Falcons' season to an early grave. They started 1-4, with a six-point loss to New Orleans, four-point loss to Miami, seven-point loss to New England and two-point loss to the Jets.
In the New York game, the Falcons also lost star receiver Julio Jones to a season-ending foot injury. Jones isn't Rodgers but the injuries have had a similar impact. While Green Bay has scored 13, 13 and 10 points in three of five games without Rodgers, the Falcons scored 13, 10, 10 and 13 during a recent five-game losing streak.
"That's part of the NFL, part of the deal," Ryan said during his conference call. "It's all about how you respond to it. We haven't done as well as we've needed to do, plain and simple. We haven't played as well as we've needed to play with the guys that are out there. Yeah, it's one of those things, you just have to deal with it, you have to move forward and you have to go with the guys that you have. Certainly, both teams have dealt with that this year."
While the Packers presumably hit bottom in Thanksgiving's 40-10 loss at Detroit, the Falcons appear to be on at least a small uptick. After getting routed by the Panthers, Seahawks and Buccaneers in consecutive weeks, Atlanta was edged 17-13 by New Orleans and rallied from a 14-0 deficit to beat Buffalo in overtime 34-31 last week.
"You know what? I think we've started play with pretty good energy," Ryan said. "We have a lot of young guys out there playing for us and I think they're finally understanding what it takes in this league and the commitment and the energy that it takes week in and week out to play well in this league. Sometimes, that takes time. Sometimes, it takes time with young guys, but I think we have a lot of rookies and a lot of second-year guys who are playing good football for us and, specifically the last two weeks, have done a great job."
One veteran who has made a difference is Steven Jackson. The Packers courted the powerhouse running back, who was coming off eight consecutive 1,000-yard seasons, during the offseason but the Falcons landed him with a three-year deal worth $12 million. Green Bay got the better of that deal by losing out on Jackson but drafting Eddie Lacy. Jackson missed several games with an injured hamstring and did next to nothing in two of his three games upon his return, partially due to getting blown out, but he carried 16 times for 63 yards and a touchdown against New Orleans and 23 times for 84 yards and two scores against Buffalo.
"We have not run the ball consistently," Smith said. "I say this: The one thing that we've done consistently is played inconsistently. That's the only consistent thing we've done all season. Steven was injured in the second game of the season and it's taken him time to get back to close to full speed. Steven's been running well the last three weeks. You have to be able to run the ball in the NFL. At some point in time during the season, you've got to do it. At the core, winning the line of scrimmage is what the NFL is all about. Always has been, always will be."
With consistency proving elusive, the Falcons are left to play the role of spoiler after five consecutive winning seasons, including four seasons of double-digits wins and playoff berths.
What's left to play for?
"Pride," Ryan said. "I think it comes down to being a professional and taking pride in what you do and loving to compete. We're football players, and when Sunday rolls around, that's what we work hard for all year. Regardless of whether or not we're going to be playing in January, we've got four more games on the schedule. It comes down to taking pride in being the best football player that you can be and the best team that you can be. I think that's been the message throughout our building."
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Bill Huber is publisher of Packer Report magazine and PackerReport.com and has written for Packer Report since 1997. E-mail him at firstname.lastname@example.org, or leave him a question in Packer Report's subscribers-only Packers Pro Club forum. Find Bill on Twitter at twitter.com/PackerReport.