No one saw this coming.

That’s the refrain after the 89-win San Diego Padres — self-proclaimed little brothers — wiped out the 111-win Los Angeles Dodgers in the National League Division Series. And of course it is. Even after a century of baseball and decades of playoff twists trying to break us of this tendency, we can’t help but collect bits of knowledge that crystalize into expectations. These are Things We Think We Know, things we carry around and reach for in the season’s most pressurized moments, only to find they have been scooped up by a rogue goose or melted in a San Diego downpour.

To understand how little we understand, it helps to remember that vast swaths of the past four years have been building toward dramatic postseason confrontations between the Dodgers and the Padres. By signing Manny Machado for $300 million prior to the 2019 season, Padres general manager A.J. Preller signaled that San Diego has serious intentions of challenging the behemoth that ruled, and still rules, the NL West. Preller, who now also carries the president of baseball operations title, has spent just about every winter and every trade deadline since then stoking an arms race with Dodgers president of baseball operations Andrew Friedman to lure the biggest stars and execute the boldest trades.

The degree to which this rivalry has dominated superstar-level player movement is hard to exaggerate. Of the 10 most productive players who have donned more than one uniform since 2018 — by FanGraphs WAR — five were on the field in this NLDS, and a sixth, Max Scherzer, at one point joined the Dodgers in a deadline deal minutes after it seemed he was headed to the Padres.

Preller’s Padres are the little brothers pushing themselves beyond normal boundaries in pursuit of their competition. You traded for Mookie Betts? We traded for Juan Soto.

So, in a sense, everyone saw San Diego trying to will this into existence. The underlying truth of a half-dozen of the biggest stories in recent baseball memory was the same: The Padres are gunning for the Dodgers. We knew it in 2019. We knew it in 2021. We knew it in August. So why, come October, was their triumph so hard to fathom?

How the Padres' winning moments came to be

Watching the Padres storm back in Game 4, erasing a three-run deficit and build a two-run lead in one inning, it became easier to diagnose the blind spot. It became more clear with each run that crossed the plate. The hitters who drove in the runs were Austin Nola, Ha-Seong Kim, Juan Soto and Jake Cronenworth. And their paths to Saturday night are instructive.

Nola was a 2020 trade deadline target. A second-year catcher at age 30, he appeared to have broken out for the Seattle Mariners, so Preller made him the centerpiece of a deal that sent Ty France, Andres Munoz and others to Seattle. Nola had batted .280/.351/.476 in 108 games for the Mariners — sensational for a backstop and very good for anyone — but hasn’t found that level in San Diego. His line in 185 regular-season games with the Padres is .254/.327/.348, and 2022 was worse than 2021.

Kim joined San Diego from the Korea Baseball Organization during a December 2020 flurry of moves. Preller signed him for four years and $28 million even though he played shortstop and third base — positions very conspicuously occupied by Machado and Fernando Tatis Jr. coming off a sensational rookie year. Kim struggled to adapt to major-league velocity in 2021, and got only 298 plate appearances, but found himself elevated into an everyday role in 2022 by necessity.

Tatis Jr. missed the entire season due to injuries and then a suspension for taking a performance-enhancing substance. Kim, as it turns out, looks like a near-elite shortstop defender who greatly improved his strikeout rates and likely dislodged Tatis from shortstop when he returns.

Soto, the 23-year-old Ted Williams reincarnation, landed on the Padres after declining an extension offer from the Washington Nationals. Preller gave up two young big-league-ready players and several highly prized prospects to get him because he was just about the best possible player anyone could hope to acquire for (at least) the next three playoff hunts.

Then, the immediate returns were … lukewarm. Even suboptimal Soto is solidly better than most hitters, but a post-trade power outage was perplexing. He hit just six homers and slugged only .390 for the Padres after putting up a .485 mark this season for the Nationals, and a .526 mark for his career. Josh Hader, the star closer acquired the same day, had a much more dramatic downturn. After the huge trade deadline jolt, the Padres didn’t even muster a better record than they had in the first half.

Then there’s Cronenworth, the lefty-swinging second baseman who delivered the decisive runs after Dodgers manager Dave Roberts brought in a southpaw to face him mid at-bat. Cronenworth came to San Diego under the cover of night and a controversy unrelated to him. Originally drafted by the Tampa Bay Rays, Cronenworth was a relatively unknown minor leaguer attached to Tommy Pham in a deal that sent Hunter Renfroe and young shortstop Xavier Edwards to Tampa. Then-Rays ace Blake Snell heard about the trade while streaming on Twitch and, in an understandable fit of anger that the Rays had traded away a useful player, dubbed Edwards a “slapd*** prospect.”

Cronenworth must have been whatever level falls below “slapd***” as he went unmentioned throughout the news cycle. As it turns out, he was the best player involved — aside from perhaps Snell, who also wound up on the Padres and beat the Dodgers in Game 3.

Padres take out the big brother Dodgers

In a lot of ways, we know too much by the end of a 162-game season. Or, more accurately, we perceive more meaning in the information we have than there really is. We see trajectories where there are none, predict patterns where there is only a completely unrelated blank slate.

These Padres went a miserable 5-14 against these Dodgers in the regular season. Just last year, our brains told us, the Dodgers fell behind a more formidable division rival, two games to one, in the NLDS. Then they won the series, never even trailing again despite some tense moments. The 2022 Padres bullpen, we thought, didn’t coalesce despite the additions of Hader and international free agents Robert Suarez and Nick Martinez. Nola is worse than we thought. Soto is having a down year, on and on.

The trend lines will never be on the Padres' side. The Dodgers were, are and probably will be the best investment in baseball, so they will probably outperform whoever over whatever stretch of five days you choose. But while there’s correlation between being the best team all season and being the best team in October, it’s not neat and tidy enough to bank on, especially with a larger playoff field adding more unpredictability.

The Padres under Preller haven’t mastered all the machinations of being the best every day. What they have done is ready themselves to mount a challenge at any time.

The little brother is wired to see those trend lines but defy them. He's told it's impossible to catch up, and therefore he throws an impossible amount of energy into doing just that. On the whole, he probably can't. But setting aside how you, I or the Los Angeles Times letters editor might feel about this reality, the borderline scientific trials of baseball’s grueling regular season tell us something different than the impromptu arm wrestling sessions of the postseason. The regular season told us the Dodgers were the finest, fittest baseball team around. The NLDS told us the Padres finally got a jump on them and pinned them.

Now they will never forget it.