There are “important” series, there are “statement” series, and then there are the ones that carry that unmistakable must-win weight.

For the Red Sox (79-65), this week’s three-game series against the Oakland Athletics of Sacramento (66-78) falls firmly in the last category.

Not because the A’s are a juggernaut. Far from it. But precisely because they’re not.

If the Sox want to keep themselves in the hunt for October baseball, dropping games to one of the league’s bottom feeders isn’t just unacceptable, it’s season sabotage.

To the layman, this weekend’s upcoming three-game set with the Yankees (80-63) is the one that feels like a must-win scenario for Boston on its surface. And make no mistake about it - those three games at Fenway are vital to this team’s playoff outlook moving forward.

But before we get to the main course that is Sox-Yanks, Boston needs to take care of business in NorCal in a big way.

Here are five reasons why this week’s series against the A’s is a must-win for Boston:

1. The Margin for Error is Gone

To put it mildly, the Red Sox haven’t given themselves much wiggle room.

The early stumbles, the injuries, the bullpen hiccups - each one chipped away at that precious margin for error.

Despite the Mariners (75-68) being four back of Boston in the wins column (as of publishing) for the second AL Wild Card spot, Seattle’s next three series are more than manageable: home for the Cardinals (72-72), home for the Angels (67-76) and away for the Royals (73-70).

If Boston doesn’t take care of business in their next three series (OAK, NYY, then OAK again), they could very well find themselves fighting with the likes of Texas (74-70) and Kansas City for the last Wild Card position in the American League, with a September that closes out with series against the Rays (71-72), Blue Jays (82-61) and Tigers (82-62), in that order.

Don’t put yourself in that position.

We’re now past the point in the season where you can just shrug off a loss to a team 20 games under .500 as “just baseball.”

Any real contender should be taking care of business against the league’s weakest clubs this time of year, especially after dropping series to the last-place Pirates (64-80) and fourth-place Diamondbacks (72-72) over the past 10 days.

If the Red Sox want to sit at the big kids’ table come September, something they haven’t done since 2021, they need to handle the A’s.

Sweeps aren’t easy, but two out of three is non-negotiable. Anything less, and the standings get a lot uglier.

2. You Can't Waste Opportunities Like This

Here’s the reality:

Opportunities to pad the win column are drying up. Outside of these final two series with Oakland, there are no more “gimmees” on Boston’s schedule.

You’ve got divisional heavyweights and teams poised for deep postseason runs waiting around the corner (sure, Tampa’s below .500, but we know what the Rays are capable of).

Games against the A’s are supposed to be the breathing room, the chance to fatten up the record before the grind resumes.

Waste this series, and you’re not just losing ground, you’re handing it away.

You can’t let the calendar turn to mid-September with a season defined by “if only we’d handled Oakland/Sacramento…”

3. Momentum Against the A’s = Momentum Against the Yankees

Momentum isn’t everything, but don’t let anyone tell you it’s nothing.

Baseball is streaky by nature, and the Sox have been teetering between flashes of brilliance and frustrating inconsistency all season long.

Beating the A’s isn’t just about the standings, it’s about building rhythm.

Take two or three in convincing fashion, and suddenly the dugout feels looser, the bats feel livelier, the bullpen breathes easier.

With Roman Anthony’s season almost certainly in the can, it becomes even more critical that inconsistent bats like Jarren Duran’s and Ceddanne Rafaela’s wake up in a real way down the stretch. And I, for one, refuse to take what Trevor Story is doing for granted. I also believe Alex Bregman's cold streak is bound to come to an end sooner rather than later.

Keep the vibes as high as possible, for Story and Bregman and everyone else. Their production is essential, and it can only be aided by Ws being added to the wins column.

Drop the series, though, and the opposite happens.

Questions creep back in, the lineup presses, and Fenway feels that familiar cloud of dread when the Yankees arrive on Friday.

Even with the dominance Boston has had over New York this season, I don’t think this roster is talented enough to withstand that type of self-inflicted weight heading into a big series this late in the year. 

In a sport where confidence is currency, the Red Sox can’t afford to be broke right now.

4. You Can't Fool Fenway

Fenway isn’t stupid.

Sox fans understand the rhythms of a long season better than most.

They’ll forgive losses to the Rangers or Mariners if the effort’s there and the losses are happening at the right time of year.

But lose a series to Oakland in September with everything still on the line? That normal baseline grumbling you hear on a nightly basis from Red Sox Nation will start sounding like a herd of banshees.

The fan base doesn’t want excuses. Just look at the comment section of any video I post of Alex Cora postgame after a loss.

They want urgency.

They want results.

They want to know this team cares as much about every pitch as they do.

Nothing sends the wrong message faster than sleepwalking through a winnable series. Especially in September.

5. Prove You Belong

This isn’t about disrespecting the A’s. They’ve got young talent and fight, and they’d love to play spoiler with pleasure.

But let’s not sugarcoat it.

If the Red Sox can’t win a series against Oakland at this stage of the season, they don’t deserve to be a part of the playoff chase.

That’s the harsh truth, and maybe it’s the wake-up call the front office needs heading into the offseason.

So yes, this week’s series is a must-win. Not mathematically, not officially, but in every way that matters.

The Sox can’t afford another stumble. The road to October goes straight through Oak - er, Sacramento. There are no detours.

Win the series.

Show some teeth.

Remind everyone that Boston baseball still has bite.

Tom Carroll is a contributor for Roundtable, with boots-on-the-ground coverage of all things Boston sports. He's a digital content producer for WEEI.com, and a native of Lincoln, RI.