Here's the rub: They did it as much in spite of Heyward as because of him.
Heyward played 142 games in his first season on the North Side and won a Gold Glove for his work in right field. His exploits in the batter's box, however, defined abysmal.
He hit .230 and set career lows in on-base percentage (.306) and slugging percentage (.325). It's not as if his stat line was undone by one cold stretch, either.
Heyward spread his mediocrity across the season, hitting above .250 in only one calendar month (June, when he hit .257) and posting an especially anemic .213/.270/.308 slash line after the All-Star break.
He did little to redeem himself in the postseason, going 5-for-48 with 13 strikeouts and starting the first three games of the World Series on the bench.
It was a disastrous season for the former All-Star. After getting paid like a superstar, Heyward hit like a scrub.
At the same time, he's still just 27 years old. In 2015, he slashed .293/.359/.439 with 13 home runs and 23 stolen bases for the St. Louis Cardinals. On the strength of his bat and superlative glove work, Heyward ranked 13th in baseball with 14.6 WAR between 2013 and 2015, according to FanGraphs' measure.
There's a reason the Cubs gave him all that cash.
Now, the question becomes: Can Heyward bounce back? And if he does, how much more dangerous can this already potent Chicago lineup become?
The bats went cold for a worrisome stretch in the National League Championship Series, but stars such as first baseman Anthony Rizzo found their stroke in time to exorcise the billy goat.
The Cubs will return with nearly the same lineup intact. Rizzo joins National League MVP Kris Bryant, shortstop Addison Russell, second baseman Javier Baez and veteran Ben Zobrist to form an enviable core.
The Cubs can also look forward to a full season from Kyle Schwarber, who was lost to a knee injury in early April and didn't return to action until the Fall Classic, when he provided an inspirational boost at the plate.
Schwarber alone should move the offensive needle northward. He flashed big-time power in his 2015 rookie campaign, cracking 16 home runs in 69 games, and is entering his age-24 season.
That means the Cubs could probably endure another anemic year at the plate from Heyward. Even after trading Jorge Soler to the Kansas City Royals for closer Wade Davis, they have a crowded outfield depth chart that features Schwarber, Zobrist, Albert Almora Jr., Matt Szczur and newly signed Jon Jay.
Heyward's serving as a $28 million-and-change part-time defensive specialist strains credulity, though. The Cubs want more out of him.
It's safe to assume Heyward wants more, too. He has an opt-out after 2018; a couple of strong seasons could equate to an even bigger payday.
Cubs mental skills coordinator Darnell Howard showcased Heyward's new, more upright swing in an Instagram post. Here's a look at it next to Heyward's swing from last season, via Corey Freedman:
Will it yield better results? We won't know until Heyward deploys it against big league pitching, but at least it shows he's trying something.
It's worth noting that Heyward has done this disappearing act before and rebounded. In 2011, after an All-Star rookie year, he hit just .227. The following season, he hiked his average to .269 and set career highs in home runs (27) and RBI (82).
The projection systems are bullish. Steamer foretells a .269/.348/.415 line with 14 home runs. The Cubs would take that with a smile.
Speaking of smiles, Heyward apparently kept his chin up through his 2016 struggles and famously delivered a rain-delay pep talk in Game 7 of the World Series.
After the season, he earned optimistic praise from Cubs president of baseball operations Theo Epstein, per Patrick Mooney of CSN Chicago:
He's got a great attitude about everything. It's just hard to make the kind of adjustments for some players in-season, because things are going so fast and you're trying to compete.
But the offseason is a great opportunity to take a deep breath, slow things down, look at video, work with your coaches, really think about the swing. Think about the bat path and make some adjustments and develop some muscle memory, work on your feel and then take it into games.
We believe in Jason Heyward and his ability to tackle things head-on and make the necessary adjustments. And I think you're going to see a much different offensive player next year.
None of this means anything until Heyward proves it between the lines. If you're the glass-half-full type, however, there are reasons to swill the Kool-Aid.
Imagine a reinvigorated Heyward and healthy Schwarber mixed with a Cubs lineup that lost leadoff man Dexter Fowler but retained everyone else of significance. Factor in the possibility that young hitters such as Baez and Russell could make a leap forward.
Heck, even Bryant, who turns 25 in January, may be climbing toward his ceiling.
There's a scenario where this offense goes from very good to scary great. More hitting from Heyward would be a key piece of that puzzle.
Chicago already won a title without much from him. Now, he has a chance to contribute to trophy No. 2.