A dark figure watched the celebrations across the country last week with a wide if unwholesome-looking grin.

From Eugene, Oregon, to Mississippi to Fort Worth, Texas, underdogs whooped and hollered and made quite a self-satisfied racket. On Sunday, Arizona jumped from unranked into the top 10, Ole Miss and Mississippi State soaked in their SEC legitimacy and TCU probably felt like a full-on, big-boy member of the Big 12 for the first time.

The dark figure, however, cackled with menace.

Everyone knows college football is haunted, which is why carnage like there was last weekend shakes up but does not shock old-timers, even if that was just the second time in the history of the AP poll that four teams ranked in the top six lost in the same regular-season week, according to ESPN Stats & Information.

You are familiar with many of the ghosts lurking about. There is the “Don’t take anyone lightly” ghost; and there is the “Don’t look ahead” ghost; and there is the “You’ll regret not signing a good kicker” ghost; and there is the “Not ready for the big stage” ghost; and there is the “SEC always gets the benefit of the doubt” ghost, etc.

And, of course, there is our suddenly invigorated dark figure. He is the “Woe to the team that believes it has arrived after a big win” ghost.

Last year, for example, Oklahoma State crushed unbeaten and third-ranked Baylor to take control of the Big 12 but then lost its next two games. West Virginia had previously upset those Cowboys only to lose six of its next seven. Stanford beat No. 2 Oregon, putting itself squarely into the national title hunt, but then it lost at USC in its next game. Tennessee beat South Carolina and promptly lost four in a row. Utah beat Stanford, then lost five in a row.

These moon-shot-to-toilet-swirl results from one week to the next happen all the time. In 1993, No. 2 Notre Dame beat No. 1 Florida State in the “Game of the Century,” but in the “Game of the Following Weekend” it lost to Boston College. In 2010, South Carolina beat No. 1 Alabama. It lost at Kentucky the next weekend, one of two SEC wins for the Wildcats.

Arizona most particularly should beware. In the past 10 seasons, unranked teams that beat a top-10 team are 45-35 in their next game, according to ESPN Stats & Info.

Upsets happen. Without them, sports, in general, would be boring and college football wouldn’t be what it is. We also love big, seemingly landmark wins, particularly when they are unexpected. We — fans and media both — often try to label such wins as transformative. As in: This win defines a season, a program’s maturation, a coach’s reputation.

That sometimes is the case, but not as often as those trying to set clear plotlines in storybook seasons would like. Simply, a big win does not a season make. It doesn’t define anything while the season remains a living and therefore mercurial thing, one that can make like Icarus and tumble to the ground just as quickly as it flew to the sun.

These ghosts of which we whimsically type are the antithesis of sports’ great clichés that became sports’ great clichés because they are so very trite and true: “Don’t get too high or too low;” “Treat every opponent the same;” and the epic, “Play one game at a time.”

What separates national contenders from merely capable football teams, in this case teams that can impress the College Football Playoff selection committee versus good teams merely headed to bowl games, is the ability to string together strong performances that create smiling scoreboards week after week. A team can enjoy a victory, perhaps even raise an extra toast to a particularly meaningful one, but an elite season is about sustained excellence — or a redundancy of just-good-enough-to-win performances — not scattered moments of celestial elevation.

The good news for our celebrating teams is their “Game of the Following Weekend” matchups are for the most part as scintillating as last week’s. It’s doubtful any hit the snooze button on preparation Monday. Still, the question now is whether these newbies to the national discourse can redouble the focus and intensity that produced last week’s momentous results.

As impressive as Mississippi State’s win over Texas A&M and Ole Miss’ victory over Alabama were, those blooms in the Magnolia State could wilt quickly if the Bulldogs and/or Rebels should get their comeuppance against Auburn and Texas A&M, respectively, on Saturday. Ole Miss fans aren’t likely to forget the experience of tailgating in the Grove, beating Alabama and then getting to celebrate the day with Katy Perry, but a fickle national audience might lose interest if the Rebels can’t produce the same sort of performance on the road (“Cause then, Rebels, you’re hot then you’re cold/You’re yes then you’re no/You’re in then you’re out”).

Arizona’s stay in the top 10 could be brief if it overlooks a wounded USC team. TCU is likely fully aware it won’t win at No. 5 Baylor if it’s nursing a hangover from the post-Oklahoma celebration.

All Hallows’ Eve is still three weeks away, so we should expect plenty of haunting results leading up to it, as this season already has been pretty spooky. Our presently relevant dark friend — “Woe to the team that believes it has arrived after a big win!” he dramatically intones again before we conclude here — however, is not going away until the selection committee speaks.