That's particularly true for the 49ers, who so many times this season have looked like one of the most likely challengers to get to the NFL's championship game.
With a quarter of the schedule remaining, there's no way to pick a favorite for the Lombardi Trophy. Not even the two teams with 11-1 records, the Falcons and Texans, or Eli Manning's Giants or Peyton's Broncos.
While there has been significant separation between the haves and the have-nots in the NFL – three division races are over and only the NFC North has no odds-on choice among the undecided sectors – none of the top teams presents overwhelming credentials for winning it all.
The 49ers enter the final quarter of the season at 8-3-1 with a 1½-game lead over Seattle in the NFC West. But with two tough road games remaining – including a Dec. 23 game against the Seahawks – San Francisco could find itself playing for the division crown when it travels to Seattle to play at one of the NFL's toughest road venues.
Several top contenders are trending upward, most notably the Broncos with a seven-game winning streak and the Patriots, who always begin peaking in November and December. The 49ers travel to play New England in a marquee Sunday night showdown on Dec. 16, a game many thought could be a Super Bowl preview – and still might be.
After San Francisco's 16-13 upset loss to the sub-.500 Rams – an unexpected defeat that now has the 49ers barely clinging to the No. 2 seed in the current NFC playoff pecking order – Atlanta just about has home-field advantage in the NFC.
Houston would pretty much secure home-field advantage in the AFC if it wins at New England next Monday night.
So that makes them the top contenders, right?
''Well, there's different championships,'' Broncos coach John Fox said. ''Your division is obviously one, everybody aspires to be in the conference championship, but at the end of the day, everybody is looking for that world championship.
''It's a great accomplishment, a tribute to the staff and coaches in that locker room. They did a fantastic job. We still have a whole quarter of the season left. We'll see what happens.''
What has been happening in Denver is encouraging because the Broncos (9-3) have been winning in a variety of ways. Yes, Manning remains the key to a first Super Bowl trip since his current boss, John Elway, retired after the 1998 title season. Throughout his remarkable comeback year after missing 2011 because of neck surgery, Manning has become more comfortable and familiar with his targets, his blockers and his running backs. That bodes well for the winter rush toward the Big Easy.
So does having a solid, physically imposing defense with a dynamic, big-play leader (linebacker Von Miller) and other playmakers.
Throw in strong special teams and it's a nice mixture. The 49ers had two parts of that mixture during their run to the NFC Championship Game last year and have been looking to upgrade the third this season, when their offense has displayed marked improvement over last season.
But the Broncos also are a developing team, a much improved one since the beginning of the season, yet still a work in progress. Getting that work done in the next two months could be a rush job.
New England was 5-3 in 2011, then won eight in a row, two playoff games at home, and lost to the Giants for the championship. The Patriots (9-3) are on another roll and it would surprise nobody if they run the table, even though they have Houston and San Francisco coming up.
Tom Brady, the only quarterback with 10 division crowns, is in the MVP conversation again. He has a formidable running game for once, and even with standout tight end Rob Gronkowski injured, Brady doesn't lack for receivers.
Any Patriots issues center on a defense that has been exceedingly inconsistent and, at times, patchwork. New England survived it a year ago, but the other AFC contenders generally are better offensively now than last season.
''As a coach I think we're always going to sit here and tell you that we're trying to improve every week and that's our goal,'' defensive coordinator Matt Patricia said, noting his units have gotten stingier. ''Certainly as the season goes on and people play together longer and are out there with each other longer then hopefully that's what's taking place.''
Houston revived its dominant, ball-hawking defense Sunday at Tennessee and has more balance than any AFC team. It also has little postseason experience, some injury concerns that have tested its depth and very little behind Andre Johnson at wide receiver. Defenses often can shut down one brilliant receiver in the playoffs with double and even triple coverage.
Baltimore (9-3) probably will hold on in the AFC North, but its warts have shown for a while, especially the last two weeks in a tight escape over San Diego and a home loss to undermanned Pittsburgh.
Many pegged the 49ers as most likely to emerge from the NFC after the Niners manhandled the Bears and outplayed New Orleans with second-year QB Colin Kaepernick emerging. Then they stumbled against the Rams, a team that also outplayed the 49ers in a tie last month.
That powerhouse defense is impressive – it ranks second in the NFL and is strong both against the run and pass – but might not be enough to carry San Francisco all the way, as it wasn't last season.
Coach Jim Harbaugh has placed his chips on Kaepernick over Alex Smith, hoping the addition of big-play potential and fast feet will complement a nasty D.
The formula looked good in a rout of the Bears and decisive victory over the Saints in the raucous confines of the Superdome. Not so good against the Rams in the Edward Jones Dome, where the 49ers gave away a game they seemingly had in hand late in the fourth quarter.
With the road to the Super Bowl almost certainly heading through Atlanta, which is 6-0 at home, the Falcons might look like a good bet. Remember, however, that they went 13-3 and were the conference's top seed two years ago, yet went out meekly against Green Bay in their first playoff game. Then New York easily bounced them out of the playoffs last year, when the wild-card Falcons only score came on a safety.
Until QB Matt Ryan, coach Mike Smith and a previously questionable defense come through in the postseason, there will be serious doubts about the Falcons.
The Packers and Bears need to get healthy to have any shot, but instead they keep seeing more players head to the infirmary. Green Bay has enough passing offense, Chicago has enough rugged defense. As for their other units, who knows? Particularly with so many injuries.
That leaves the juicy prospect that if Peyton Manning can get there, younger brother Eli and the Giants will be waiting. The Giants sprang to life even later in 2011 – in the final two weeks of the season – and have the key elements every contender desires: a winner at quarterback, strong pass rushers, a variety of playmakers and experience.
And they're a team that gives the 49ers fits if the two were to meet again in the playoffs. But after losing Monday at Washington, New York must first worry about holding onto its one-game lead in the NFC East.
Then again, with no clear favorites in what has been an unusual NFL season, leave open the unprecedented possibility of two wild-card teams making their way to the Superdome in February.
And depending on how things shake out the rest of the way, one of them could even by the Niners.