Paul Sullivan: Ecstasy or heartbreak? A roller-coaster Chicago Cubs season has reached the fork in the road.

It all comes down to the final week for the Chicago Cubs, a team that has toyed with its fans emotions from opening day.

Six road games against two playoff-bound teams, the Atlanta Braves and Milwaukee Brewers, to decide whether the Cubs are October-worthy.

For anxiety-ridden Cubs fans who’ve followed their team from Day 1, the obstacles to the postseason party couldn’t be more pronounced. One is the best team in baseball, with a lineup ESPN speculated could be the greatest of all time. The Cubs are not of the Braves’ “caliber,” some might say, but they did beat the Braves in two of three games at Wrigley Field in early August.

The other is the Cubs’ longtime irritant from up Interstate 94, the traditionally overachieving Brewers, who have replaced the St. Louis Cardinals as the team’s archrival to a generation of fans. The Cubs’ turnaround this season can be traced directly to a wild 7-6, 11-inning win over the Brewers on July 4 in Milwaukee, a game starter Justin Steele aptly described as “drunk.”

By Sunday night fans will know whether a Cubs season defined by peaks and valleys will end in ecstasy or heartbreak.

The Cubs enter Tuesday one game ahead of the Miami Marlins for the third National League wild-card spot and tied with the Arizona Diamondbacks, who hold the tiebreaker over the Cubs. If the Cubs go 6-0 they’re in, no matter what the Marlins or Cincinnati Reds do.

The Cubs can’t afford to finish tied for the third spot, as the Marlins and Reds also own the season series tiebreaker. Major League Baseball’s shortsighted decision to eliminate Game 163s ensured someone would one day lose out on a playoff spot via the head-to-head tiebreaker.

MLB didn’t want to have to wait to arrange its precious postseason TV schedule and killed Game 163s in spite of their rich history. That means the Cubs season can end in one of three ways: They earn a wild card, blow a wild-card spot they had in their hand or miss the playoffs by ending in a tie.

The third option — getting to the finish line with the same record as another contender and still going home — might be the worst-case scenario. The Cubs have experienced some cruel endings in our lifetimes, but at least they got to finish them on the field. Death by tiebreaker would be the cruelest fate of all, especially after a season as stomach-churning and entertaining as this one.

The Cubs played two Game 163s: the memorable win over the San Francisco Giants in the 1998 wild-card tiebreaker and the loss to the Brewers in the 2018 divisional tiebreaker that served as a turning point in the downfall of the 2016 World Series champions. The Cubs went on to lose to the Braves in the 1998 division series and to the Colorado Rockies in the 2018 wild-card game.

This week also could serve as a litmus test for manager David Ross, who has tried to right the ship after a 3-10 skid before the weekend sweep of the Rockies.

Ross needs more of his stars to step up if the Cubs hope to get past this final hurdle. Three hitters have basically carried the lineup in September: right fielder Seiya Suzuki (hitting .375 in the month with seven home runs and 22 RBIs), second baseman Nico Hoerner (hitting .322 with a .406 on-base percentage) and first baseman Cody Bellinger (six home runs and 18 RBIs).

The losses of Jeimer Candelario and Nick Madrigal to injuries have been tough to swallow, but if the rest of the lineup produces as expected, the Cubs should be OK.

Ross opted to skip veteran Kyle Hendricks for the Braves series, using Jameson Taillon and Marcus Stroman after Steele. All three starters need to be at the top of their game to avoid a devastating sweep by a Braves team seemingly making history by the day.

Steele, an NL Cy Young Award candidate and the undisputed ace of the staff, struggled in his last two starts, allowing 12 runs over nine innings. This is his first pennant chase, and the pressure has increased on him to pitch like an ace.

Taillon, whose last start was skipped, has a 6.11 ERA in the first inning and 6.43 in the second. He often recovers, albeit after putting the Cubs in a hole.

Stroman was subpar in a three-inning start Saturday in his return to the rotation from hip and rib injuries that had sidelined him since July. His quick comeback attempt is laudable, but is starting someone not fully stretched out a risk to the depleted bullpen?

Ross’ three-headed bullpen solution also has taken a hit with closer Adbert Alzolay on the injured list and Mark Leiter Jr. absent from the mound since giving up three runs Wednesday in a 13-7 loss to the Pittsburgh Pirates. That leaves it mostly up to workhorse Julian Merryweather, whose career-high 67 appearances and 69 1/3 innings are more than double his previous highs set last year with the Toronto Blue Jays.

The Cubs bullpen has six blown saves in 10 opportunities in September with a 4.15 ERA. With the recent bullpen issues, Ross could use more length from his starters. But whether he would ask them to extend themselves this week is another question. Ross lifted Taillon after he allowed one hit in six shutout innings and only 77 pitches on Sept. 8, igniting a debate on his handling of starters.

Ross explained that a lot of factors went into the decision, including “how much bullpen availability I have, how fresh those guys are, blah, blah, blah, blah, blah, blah, blah.”

That’s seven “blahs” if you’re keeping score at home.

Has a starter ever changed Ross’ mind to let him stay in the game?

“Change my mind? If I’m set on something, no,” he replied. “I’m not going to let them.”

Ross added that if a starter coming out wants to argue, “that’s fine” with him. But the answer is still no.

“I don’t ever want anybody who doesn’t want to (continue),” he said. “I’ve been around those guys. Those guys aren’t fun to have on your staff. ... If they are pissed off to come out of the game, perfect. That’s what I want.”

So a season that has gone through more ups and downs than any in recent memory comes down to this final week, when anything can happen. That’s why baseball added a third wild-card spot to both leagues and why a team only eight games over .500 remains in contention.

If the Cubs make the postseason after being 10 games under .500 on June 8, it would rank as one of the most impressive comebacks in team history.

And if not, it’ll be “blah, blah, blah, blah, blah, blah, blah” all over again.

Time to find out how the story ends.