The Chicago Cubs being who they are, it was always a certainty that they would, at some point this year, immolate in impressive fashion. Perhaps press baron Sam Zell would auction off their best players. Perhaps the city’s foie gras ban would sap them of their vital power. Any way you figured, it was always clear they would make a friend of epic failure. Whether they’re doing so now, or whether their bad week is a mere prelude to the loss of an eight-run lead in the ninth inning of Game 7 of the World Series, has yet to be determined. If you’re betting, though, bet on the latter.

Lining up the facts, things look ugly. Heretofore invincible at home, the Cubs had lost four straight at Wrigley Field going into last night’s game. Perhaps worse, woe and doom surrounds twin aces Carlos Zambrano and Rich Harden. Given the club’s recent history, the safe assumption is that neither will ever pitch well again. Still, no one need panic, and fans of no other team ought to celebrate.

Zambrano’s injuries are probably the more frightening. The beating heart of the Cubs for the last six years, Big Z first came up lame in late June, when he went on the disabled list with a strained shoulder. He came back strong: Through August 3, he’d rung up a 2.76 ERA and a K/BB ratio better than 2:1, all the while tossing his usual bowling-ball sinker and praising the heavens with a finger pointed toward the sky after every tough inning — but he’s recently unraveled. Over his last five starts, he’s tossed the ball as hard as ever, but seemed to have little idea of where it was going: An 8.10 ERA, paired with a 19/17 K/BB ratio and a rather strained-looking delivery, had observers fearing the worst, and when he had to skip a start Sunday, it reassured no one. He came up lame Tuesday, and given his recent shabby performance and how hard he’s been worked over the years, it would surprise no one if he’s thrown his last effective pitch on the year, and perhaps his last, full stop.

Harden’s issues are nearly as disheartening for the shirtless faithful in the bleachers. Per inning, he’s been every bit as good as Milwaukee’s C.C. Sabathia since coming over to the National League in a trade this summer, striking out a preposterous 75 men in 54 innings and giving up 1.50 earned runs per nine. But he last pitched August 29 and isn’t scheduled for another start until next Tuesday.

“We talked about making sure we did this six weeks ago,” general manager Jim Hendry told the Chicago Tribune, and as the incredibly fragile Harden hasn’t started 20 games in a season since 2004, that’s entirely believable. Still, given that his fastball was down to 90 mph in his last start, and given his injury history, one wouldn’t want to bet anything substantial on his making any playoff starts, or at least any especially effective ones. Together with Zambrano’s injury, it’s enough to leave every goat in Illinois gloating.

In truth, though, the Cubs will most likely be fine even if Zambrano and Harden spend the rest of the calendar year playing video golf and taking in art films at the Music Box just blocks west of Wrigley. There could be reason to doubt that, as their rotation has been perhaps their signal strength. (Its ERA of 3.75 was, going into last night’s game, tied with Milwaukee’s atop the league.) Crucially, their starters were equally as good at home as on the road. That’s not true of the team’s offense — while more than solid on the road, scoring 5.02 runs a game, Chicago has been devastating at home, scoring 5.73 — and so there’s an angle from which it would seem that the sudden lopping off of the top fifth, or two-fifths, of the rotation would be disproportionately painful.

For a team to have a top rotation, though, it takes more than two starters, and the Cubs certainly have that. As discussed in this space yesterday, Ryan Dempster is a more than plausible Cy Young candidate, and both Ted Lilly (13-8, 4.23 ERA) and Jason Marquis (9-8, 4.46) have been solid no. 3- or no. 4-type starters, the kind who can win the third game of a playoff series if the lineup swings well and the relievers do their work. Swingmen Sean Marshall and Chad Gaudin, for their parts, are reliably average types, in no way adequate substitutes for Zambrano and Harden, but perfectly capable of filling out a championship rotation through the end of September and even into October given the right support.

With a strong and occasionally magnificent offense, and a bullpen that ranks fourth in the league in ERA and boasts the formidable trio of Carlos Marmol, Kerry Wood, and Jeff Samardzija, there’s little reason to think the Cubs couldn’t win a pennant with Dempster, Lilly, and Marquis fronting their rotation, and that’s why their late sufferings shouldn’t be taken for the onset of catastrophe. That will come — I wouldn’t be surprised to see Lake Michigan rise in a great crest and sweep away such stars as Aramis Ramirez and Geovany Soto sometime during the NLCS. But if they don’t win the pennant, it probably won’t be because their aces went down. It took more than Zambrano and Harden to make them this the best team in the league, and it will take more than their loss to make them something less.

tmarchman@nysun.com