As you watch the Giants unravel like a planet-size ball of yarn, perhaps you picture Brian Sabean in his AT&T Park suite, thinking to himself, “These are our guys. They’ve done it before. By God, they’re gonna bounce back next year.”

You’d be wrong.

The Giants’ executive vice president sensed there was something wrong as early as spring training, and by May, he knew there was no way out. Not for a season that took on a bizarre life of its own.

Sabean, general manager Bobby Evans and CEO Larry Baer shared a trust in this year’s roster during the winter, and with good reason. Despite a regrettable second half of the 2016 season, the Giants scored a memorable wild-card victory over the Mets, then engaged the eventual champion Cubs in a lively Division Series until the bitter climax to Game 4. Most preseason forecasts had them winning 88-90 games this year.

What followed was a long-standing baseball truism: Things can radically change, and with great haste. The Giants were a hopeless case in ’96 and made the playoffs the following year. Just when the 2013 season appeared to signal the end of the Giants’ run, they came back with another world title. And the list goes on.

“The more time you spend in this game, the more you realize it’s a lot like life, something so human, it can’t be predicted or explained,” Sabean said during a lengthy interview with The Chronicle. “Because you’re so immersed in it, you develop an ESP for things. You can read people, body language, group dynamics.

“Even during camp (in Arizona), I felt some angst,” he said. “The wheel was never round.”

By the end of April, the season had become “a wake-up call,” he said. “We hit rock bottom so hard, we realized how tough it is to win a major-league game, win a series, have a winning week. You almost start doing the math too early: How the hell are we gonna overcome this? It’s different if you’re just going against one team, but we were behind the 8-ball on three teams (the Dodgers, Diamondbacks and Rockies). And it continued to get worse.”

For the moment, Sabean said, “We just need to get the season finished, take a step back, decompress, and not get blindly negative. We can’t go overboard, like, ‘Nobody can play. Nobody should come back on this team.’ We still believe in our core players. But we have to put a fresh look on things. Whatever culture we created, whatever atmosphere, that window is closed.”

There’s a popular and well-reasoned theory that the Giants are stuck. Among the players they’d like to unload, off-years and contractual obstacles have reduced value to a pittance. The farm system gets consistently low ratings, and among the prospects who got a look this year, only a few — Ty Blach, Chris Stratton, Kyle Crick, with flashes from Christian Arroyo and Austin Slater — made a lasting impression.

Worse yet, with power hitting all the rage this season, the Giants rank dead last in the majors in home runs. And they have the oldest collection of position players in the National League.

“We definitely need to get younger, more athletic and improve our defense, which has been atrocious,” Sabean said. “We’ve never been known as a big power team, unless you go back to 2000, when we were almost like an American League team (finishing with 226 homers). And let’s face it, how many free agents are going to come here? They’re not. For two reasons: the ballpark and the California taxes. That’s just a fact.

“So we’ll have to be very open-minded and aggressive on the trade front. We’re gonna have to be creative, and in some cases, bold. I’ve been thinking about how we can re-invent ourselves since the All-Star break.”

Conclusions safely drawn:

•The Giants figure to head into next season with an experienced rotation — Madison Bumgarner, Johnny Cueto, Jeff Samardzija and Matt Moore — with one of their young pitchers filling the fifth slot. That’s a solid group if they all stay healthy.

•The bullpen figures to be significantly different, and better, with Mark Melancon coming off surgery, Will Smith returning from a lost season and Sam Dyson proving to be one of Evans’ better moves.

•Between his concussion issues, burdensome contract (owed $64 million through 2021) and streaky hitting — unwatchable during the down times — first baseman Brandon Belt has exhausted the team’s patience. To be overly critical is simply not fair, with so many other players underperforming, and Belt is the most proven power hitter on the roster. He wouldn’t appear to be going anywhere, but sources indicate that manager Bruce Bochy would welcome a new look at this position.

•Few players in Giants history have been more beloved or influential than Hunter Pence. If you questioned his worth to the team in spring training, you’d be considered a lunatic. But this season has brought an alarming disintegration in all phases of his game. He isn’t nearly the same player. He’s owed $18.5 million next season, the final year of his contract, and he has a full no-trade clause. If he returns, barring a dramatic resurrection, his role is certain to be diminished.

•The rest of the outfield is a disaster. The Giants can live with Denard Span’s bat, but not his defense, making it likely he gets moved to left field — perhaps in a platoon — if he’s still with the team. Gorkys Hernandez is a gifted defender, but not built for the everyday grind as a hitter. Nothing short of a major overhaul will be acceptable.

•If the Giants still believe in Pablo Sandoval at third base, they’re hopelessly stuck in the past. Arroyo may yet develop into the hitter who showed so much promise in the early season, and he can field the position. But his absence of playing time (because of injury) makes him somewhat of a mystery, and Ryder Jones isn’t considered ready to be a starter next season.

“It’s incumbent on us to introduce more power and run production into the lineup,” Sabean said. “We know the legacy that’s been built, what the fan base has come to expect, and we don’t want this to be a lengthy turnaround. Can I promise you it will be quick? No. The first step is going from last place to being competitive. But I can tell you this: We won’t be outworked. We want to be different in every possible way that can change our fortunes. Because we’re not used to doing business like this.”

Bruce Jenkins is a San Francisco Chronicle columnist. Email: bjenkins@sfchronicle.com Twitter: @Bruce_Jenkins1