SAN FRANCISCO – At the end of a 162-game regular season during which they faced each other 19 times, the San Francisco Giants had won 107 games, the best in baseball and most in franchise history. The Los Angeles Dodgers had won 106 games, the second best in baseball and the same as they had in 2019 when the Washington Nationals upset them in the NLDS en route to a championship.

In the second half, both teams had won 50 games (the Giants played and lost two more than the Dodgers did). They spent the last 40 games of the season separated by fewer than three games in the standings. Essentially neck-and-neck, as the Dodgers dominated but ultimately failed to gain on the Giants.

Because they share a division, the Dodgers were forced into a wild-card game against the St. Louis Cardinals, which they won in the bottom of the ninth inning, giving them 107 wins of their own going into the historic heavyweight NLDS against the Giants.

The winners of the first four games went like this: Giants, Dodgers, Giants, Dodgers. One apiece in L.A. and San Francisco. Of course.

Not one of those games featured a single lead change. Turns out it’s tough to catch each other when you’re moving at exactly the same speed.

That brings us to now: the eve of the Game 7-iest Game 5 ever. The Giants have won 109 games this year. The Dodgers have won 109 games this year. Thursday will be their 24th and necessarily final meeting of 2021.

“I was hoping it wouldn't come to this. I was hoping we would win in three straight,” Dodgers manager Dave Roberts said on Wednesday. “The way that the regular season played out, absolutely, I'm sure it was inevitable.”

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The smart conventional wisdom (not to mention the scholarly analysis) says that you can’t tell which of two baseball teams is better over a small sample size. This means MLB’s postseason is inherently flukey, prone to getting hijacked by an inferior team on a hot streak. It's part of what makes it so memorable. And why the one-game wild-card format is especially controversial and exciting.

But here’s the thing: We already ran the six-month experiment and what we learned is that the Giants and Dodgers are remarkably well-matched (although you could argue that it’s meaningful that the Giants’ single-game lead in the standings reflects a slight series edge going 10-9 against the Dodgers).

Preseason predictions would tell you that if you let them play on indefinitely, the Dodgers would eventually emerge as “better.” But we don’t have time for that. Instead we gave them five games and found them to still be effectively equal through four.

So now we’ll give them a new test, a slightly different one.

Any single game in a season is not a reliable barometer of relative ability. But a win-or-go-home Game 5 in a rivalry that has spanned a century but never been waged in a postseason setting is not just any single game. Both teams enter with the same stakes, on the same rest. The factors that differentiated their storylines all season will be front and center as the Dodgers start the same pitcher who made the final out to secure a World Series win one year ago and the Giants start a 24-year-old who pitched more than 60 innings for the first time this year and made his October debut throwing 7⅔ shutout innings in the first game of this series. The Dodgers’ Roberts is managing in his sixth straight postseason appearance. The Giants’ Gabe Kapler is managing in his first, letting his team lean on the words of Buster Posey and the Brandons.

Kapler said that the intensity down the stretch as the Giants gritted through some of their best baseball to stay just ahead of the Dodgers prepared him for the playoffs. The biggest difference in October, he noted, is that every game — especially this game — is all-hands-on-deck. With built-in off days, everyone is available. That goes for both teams, although Roberts would prefer to not pitch Max Scherzer out of the bullpen so he’s available for the first game of the NLCS.

“But I've been known to change my mind,” he said. “So we'll see.”

Any game that might feature Scherzer in relief is exceptional. It won’t measure the same thing that a full season does — or a simulated set of a thousand simultaneous seasons — but it’ll have to suffice. All the other division series are over — the whole baseball world is waiting, the progression of the postseason left in limbo, until we can determine which of these two teams is better. So one more game it is: The winner will be the most successful team left standing, and the loser will be the most successful team spending the rest of the month at home.

“So if you have a pulse or you're a sports fan, you better be watching Dodgers-Giants,” Roberts said.

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Despite those circumstances, Kapler said there won’t be anything unexpected in how he sets his lineup or deploys certain matchups. And similarly, he’ll be prepared for anything the Dodgers do with respect to relief pitching.

“What I'll say is I'm not going to be surprised by anything. Dodgers aren't going to be surprised by anything,” he said. “It's where we are.”

That’s the thing about division rivalries: It’s tough to keep any tricks up your sleeve.

“I think the playbook is kind of ‘we know each other's playbook,’ so now it just goes old school, we're going to run the ball to the right and you're going to have to stop us. It's the Vince Lombardi,” Roberts said about the effects of familiarity between the two teams.

“We know what we do, they know what we do … now it's about going out there and executing, and the best team wins.”

Postgame platitudes aside, there’s something to that. Throughout the summer, examinations of the Dodgers’ and Giants’ dual dominance centered on the shared DNA of their front offices. Farhan Zaidi was lauded for what he built in San Francisco so soon after leaving Andrew Friedman’s side in L.A. Once considered the platonic ideal of a savvy team that spends money, the Dodgers suddenly had a worthy challenger in the sport of roster construction.

All of that is true, and how we got here. But come first pitch on Thursday, there will be nothing left for the front offices to do but sit back and sweat while the game unfolds. Maybe they’re equally good teams, but one of them is going to play better and that’ll be the difference.

“Obviously both teams know each other well,” as Posey said after his team suffered a Game 4 loss to send the series back north to his home park. “A lot of these guys have played against one another for a long time. This is why you play, really it boils down to competing and execution, and it's pretty much as simple as that.”